Fluorinated derivatives of 3-hydroxypyridin-4-ones

ABSTRACT

Provided are compounds of Formula I which are derivatives of 3-Hydroxypyridin-4-ones. The compounds may be used in treatment of a medical condition related to a toxic concentration of iron. The compounds may be used for preparation of a medicament for treatment of a medical condition related to a toxic concentration of iron. The medical condition related to a toxic concentration of iron may be selected from the group consisting of: cancer, pulmonary disease, progressive kidney disease and Friedreich&#39;s ataxia.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority as a continuation-in-part application to U.S. patent application Ser. No. 14/735,718, filed Jun. 10, 2015, which is a divisional application to U.S. patent application Ser. No. 13/382,130, now U.S. Pat. No. 9,073,865, filed Jun. 21, 2012, which is the U.S. national stage of PCT Application No. PCT/CA2010/001027, filed Jul. 5, 2010, which claims priority from U.S. Provisional Application No. 61/222,979, filed Jul. 3, 2009, the entire contents of which are each expressly incorporated by reference.

BACKGROUND

The occurrence of in vivo iron toxicity in the human body can be categorized into iron overload and non-iron overload conditions. Iron overload conditions are common in thalassaemia patients through chronic blood transfusions and in hereditary haemochromatosis patients. Non-iron overloaded conditions include anthracycline mediated cardiotoxicity, viral infections, neurodegenerative diseases, photo induced damage, and proliferative conditions. The potential use of iron chelators in the treatment of a variety of diseases is reviewed in Tam et al., Current Medicinal Chemistry, 2003, 10, 983-995 and Hider et al., BioMetals, 2007, 20, 639-654.

At present, there are several iron chelator drugs that have reached the market. Examples of those include deferiprone (Ferriprox™), ICL670 (ExJade™), dexrazoxane hydrochloride (Zinecard™) and desferrioxamine mesylate (Desferal™). However, only two of these compounds, namely deferiprone and ICL670, are orally active for the removal of iron in iron-overloaded diseases.

SUMMARY

In designing 3-hydroxypyridin-4-one that will lead to improved brain exposure, one approach is to increase the lipophilicity of the chelator via the introduction of a trifluoroethyl group at the C2 or C5 or C6 position of the 3-hydroxypyridin-4-one (US20080242706). This invention is based in part on compounds with a trifluoroethyl group at the N1 position, or a 2-difluoroethyl group at the C2 position of the 3-hydroxypyridin-4-one skeleton. The use of low molecular weight substituents is also considered in the design of new bidentate 3-hydroxypyridin-4-one ligands (L). A ML_(n) complex is formed upon complexation with a metal (M), for example FeL₃.

Amines are known to have favorable interaction with predominately negatively charged phospholipids head groups at the BBB (blood brain barrier). In general, bases penetrate better into the CNS (central nervous system) (Chapter 10, Blood Brain Barrier in Drug-Like Properties: Concepts, Structure Design and Methods, by Edward H. Kerns and Li Di, Academic Press, Elsevier 2008). Herein, a series of amino derivatives with trifluoroethyl at the C2 or N1 or C5 or C6 position of the 3-hydroxypyridin-4-one backbone are designed and synthesized. Selected examples of those compounds are 2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one (Apo7041), 5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one (Apo7053), and 6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo7021), and 2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo7067).

This invention is based in part on a serendipitous discovery that amine derivatives such as 2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one (Apo7041) are less favorable than deferiprone in BBB penetration in cassette dosing BBB studies in rats. Physicochemical studies confirm that Apo7041 (pKa=3.51) is less basic than normal aliphatic amines. Certain selected amine derivatives of this invention are weak bases and have pKas in the range of 3.5 to 6.0.

The weak bases of this invention are lipophilic and may also possess the ability to accumulate in the acidic compartment of biological systems. In addition, the metal chelates of compounds of this invention may have a distinctive property of being stable at significantly lower pHs than the metal chelate of deferiprone. The compounds of this invention may be useful in biological conditions such as treatment of cancer, inflammatory lung disorders and renal disease wherein the therapy requires a weak base to accumulate in the acidic compartment and sequester free iron under slightly acidic conditions to form a stable ferric chelate, which results in the removal of iron.

On the other hand, fluorinated derivatives of 3-hydroxypyridin-4-ones with a basic amine with pKa >6.0 have different properties than the weakly basic amines such as Apo7041. An example of such is 2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo7067, pKa=6.1). Apo7067 is more lipophilic than deferiprone and readily penetrates the BBB in cassette dosing BBB studies in rats.

Non-amino fluorinated 3-hydroxypyridin-4-ones derivatives of this invention are generally more lipophilic than deferiprone and can accumulate in the brain region. Examples of those compounds are 3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo6995), 3-hydroxy-2-(hydroxymethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo7064), 2-(2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (Apo7080) and 2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (Apo7078). Compounds such as Apo6995 may be useful as low molecular weight iron chelators for accumulation in the brain. One possible use is the treatment of Friedreich's ataxia, wherein the site of iron removal or redistribution is in the brain.

In illustrative embodiments of the present invention there is provided a compound of Formula I:

wherein G¹ is H, C₁-C₄ alkyl, CH₂OH, CH₂NR¹R², CH(R⁴)CF₃, CH(R⁷)CF₂H, NR¹R², or

G² is H, C₁-C₄ alkyl, cyclopropyl or (CH₂)_(n)CF₂R³; G³ is H, C₁-C₄ alkyl, CH₂OH, CH₂NR¹R², CH(R⁶)CF₃, CH₂-A-OH, CH₂-A-NHR⁹ or

CH₂CF₃ or and G⁴ is H, C₁-C₄ alkyl, halo or CH(R⁵)CF₃; n is 1, 2 or 3; R¹ and R² are either (a) two independent groups or (b) together form a single ring group; R¹ and R², when independent groups, are independently selected from the group consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, and propargyl; R¹ and R², when together form a single ring group, are selected from the group consisting of: piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholinyl, and piperidinyl; R³ is H or F; R⁴ and R⁷ are independently selected from the group consisting of: H, OH, NR¹R², imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl and -A-NH—R¹⁰; and when R⁴ or R⁷ is imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl or -A-NH—R¹⁰, a point of attachment of R⁴ or R⁷ to the CH moiety of G¹ is an N atom of R⁴ or R⁷; R⁵ is C₁-C₄ alkyl; R⁶ is H or OH; R⁵ is selected from the group consisting of: NR¹R², imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl and -A-NH—R¹⁰; and when R⁸ is imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl or -A-NH—R¹⁰ a point of attachment of R⁸ to the CH moiety of G⁴ is an N atom of R⁸; R⁹ and R¹⁰ are independently H or C₁-C₄ alkyl; A is —NH—(CH₂)_(m)—CO— or an alpha amino acid residue; m is 1, 2 or 3; and provided that: at least one of G¹, G², G³ and G⁴ comprise at least one fluorine moiety; when G¹ is CH(R⁴)CF₃ and R⁴ is H or OH, then either (i) G³ is CH₂NR¹R², CH₂-A-OH, CH₂-A-NHR⁹ or (ii) G⁴ is halo or CH(NR¹R²)CF₃; and when G³ is CH(R⁶)CF₃, then G¹ is CH₂NR¹R², CH(R⁴)CF₃, CH(R⁷)CF₂H, NR¹R² or

In illustrative embodiments of the present invention, there is provided use of a compound described herein for treatment of a medical condition related to a toxic concentration of iron. The use may be for preparation of a medicament. The medical condition related to a toxic concentration of iron may be selected from the group consisting of: cancer, pulmonary disease, progressive kidney disease and Friedreich's ataxia.

In illustrative embodiments of the present invention, there is provided a method of medical treatment comprising administering a therapeutically effective amount of a compound described herein to a subject having or suspected of having a medical condition related to a toxic concentration of iron. The medical condition related to a toxic concentration of iron may be selected from the group consisting of: cancer, pulmonary disease, progressive kidney disease and Friedreich's ataxia.

Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic representation of E_(1/2) zone of established drugs such as deferiprone and desferroxamine B. When a ferric chelate has an E_(1/2) value that falls below −320 mV (mV vs. NHE), the chelate is not redox active and its properties fall within the E_(1/2) zone of established drugs such as deferiprone and desferroxamine B, and body protein such as transferrin. Compounds of Formula I have E_(1/2) values that fall within the zone between ferrioxamine B (iron chelate of desferrioxamine B) and Fe(deferiprone)₃. Both deferiprone and Apo7041 are 3-hydroxypyridin-4-one derivatives. Deferiprone is 3-hydroxy-1,2-dimethylpyridin-4(1H)-one and Apo7041 is 2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one.

FIG. 2 is a diagrammatic representation of the cyclic voltammetry (CV) of the Fe chelate of three representative compounds of Formula I, Apo7041 (G²=Me, G¹=CH(NMe₂)CF₃, G⁴=H, G³=H), Apo7053 (G²=Me, G¹=Me, G⁴=CH(NMe₂)CF₃, G³=H), Apo7069 (G²=CH₂CHF₂, G¹=Me, G⁴=H, G³=H).

FIG. 3A is a diagrammatic representation of a Job's Plot of Apo 7053 5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one, a compound of Formula I.

FIG. 3B is a diagrammatic representation of a Job's plot for Fe-Apo7041 system with [Fe]_(total)+[Apo7041]_(total)=8×10⁻⁴ M in 0.1 M MOPS at pH 7.4.

FIG. 4 is a diagrammatic representation of the Fe speciation plot of the Fe:deferiprone system in the ratio of 1:10 with [Fe]=1×10⁻⁶ M and [deferiprone]=1×10⁻⁵ M.

FIG. 5 is a diagrammatic representation of the Fe speciation plot of the Fe:Apo7041 system in the ratio of 1:10 with [Fe]=1×10⁻⁶ M and [Apo7041]=1×10⁻⁵ M.

FIG. 6 is a diagrammatic representation of the protonation of the chelate of Apo7041. The Fe-chelate of a weak base is a proton sink. Protonated FeL₃ species via protonation of the amine moieties FeL₃ to FeL₂ are present in acidic medium. Conversion of FeL₃ to FeL₂ occurs only at very low acidic pH.

FIG. 7 is a diagrammatic representation of the degradation of FeL₃ to FeL₂ for neutral 3-hydroxypyridin-4-ones.

FIG. 8 is a diagrammatic representation of the Apo7041 ligand. The steric bulk at the C2 position is designed to block phase II metabolism involving glucuronidation of the C3 oxygen.

FIG. 9. A diagramatic representation showing that a compound of formula I and deferiprone suppresses the formation of the hydroxybenzoic acid when benzoic acid is treated with hydrogen peroxide and iron salts. The y axis refers to the total concentration of 2-hydoxybenzoic acid, 3-hydoxybenzoic acid, and 4-hydoxybenzoic acid formed (unit: μM).

FIG. 10 is a diagrammatic representation of the neuroprotective action of deferiprone on MPP+ treated SV-NRA cells. MPP⁺ treatment decreased cell viability when compared to untreated vehicle control. Treatment with deferiprone, an iron chelator drug resulted in about 20% increase in cell viability (p<0.05).

FIG. 11 is a diagrammatic representation showing the neuroprotective action of Apo7021, a compound of formula I, on MPP+ treated SV-NRA cells.

FIG. 12 is a diagrammatic representation showing the neuroprotective action of Apo7060, a compound of formula I, on MPP+ treated SV-NRA cells.

FIG. 13 is a diagrammatic representation showing the neuroprotective action of Apo6995, a compound of formula I, on MPP+ treated SV-NRA cells.

FIG. 14 is a diagrammatic representation of the Fe speciation plot of the Fe:Apo7323 system in the ratio of 1:10 with [Fe]=1×10⁻⁶ M and [Apo7323]=1×10⁻⁵ M.

FIG. 15 is a diagrammatic representation of the Fe speciation plot of the Fe:Apo7067 system in the ratio of 1:10 with [Fe]=1×10⁻⁶ M and [Apo7067]=1×10⁻⁵ M.

FIG. 16 is a diagrammatic representation of the Fe speciation plot of the Fe:Apo7435 system in the ratio of 1:10 with [Fe]=1×10⁻⁶ M and [Apo7435]=1×10⁻⁵ M.

FIG. 17 is a diagrammatic representation of the Fe speciation plot of the Fe:Apo7056 system in the ratio of 1:10 with [Fe]=1×10⁻⁶ M and [Apo7056]=1×10⁻⁵ M.

DETAILED DESCRIPTION

Compounds of the present invention comprise compounds having a structure according to Formula I:

wherein

G¹ is H, C₁-C₄ alkyl, CH₂OH, CH₂NR¹R², CH(R⁴)CF₃, CH(R⁷)CF₂H, NR¹R², or

G² is H, C₁-C₄ alkyl, cyclopropyl or (CH₂)_(n)CF₂R³;

G³ is H, C₁-C₄ alkyl, CH₂OH, CH₂NR¹R², CH(R⁶)CF₃, CH₂-A-OH, CH₂-A-NHR⁹ or CH₂CF₃ or

and

G⁴ is H, C₁-C₄ alkyl, halo or CH(R⁸)CF₃;

n is 1, 2 or 3;

R¹ and R² are either (a) two independent groups or (b) together form a single ring group;

R¹ and R², when independent groups, are independently selected from the group consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, and propargyl;

R¹ and R², when together form a single ring group, are selected from the group consisting of: piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholinyl, and piperidinyl;

R³ is H or F;

R⁴ and R⁷ are independently selected from the group consisting of: H, OH, NR¹R², imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl and -A-NH—R¹⁰; and when R⁴ or R⁷ is imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl or -A-NH—R¹⁰, a point of attachment of R⁴ or R⁷ to the CH moiety of G¹ is an N atom of R⁴ or R⁷;

R⁵ is C₁-C₄ alkyl;

R⁶ is H or OH;

R⁸ is selected from the group consisting of: NR¹R², imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl and -A-NH—R¹⁰; and when R⁸ is imidazolyl, 1-2-4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl or -A-NH—R¹⁰ a point of attachment of R⁸ to the CH moiety of G⁴ is an N atom of R⁸;

R⁹ and R¹⁰ are independently H or C₁-C₄ alkyl;

A is —NH—(CH₂)_(m)—CO— or an alpha amino acid residue;

m is 1, 2 or 3; and provided that:

at least one of G¹, G², G³ and G⁴ comprise at least one fluorine moiety;

when G¹ is CH(R⁴)CF₃ and R⁴ is H or OH, then either (i) G³ is CH₂NR¹R², CH₂-A-OH, CH₂-A-NHR⁹ or (ii) G⁴ is halo or CH(NR¹R²)CF₃; and

when G³ is CH(R⁶)CF₃, then G¹ is CH₂NR¹R², CH(R⁴)CF₃, CH(R⁷)CF₂H, NR¹R² or

When G¹ comprises a fluorine moiety, then G¹ is selected from the group consisting of: CH(R⁴)CF₃, CH(R⁷)CF₂H, and

When G² comprises a fluorine moiety, then G² is (CH₂)_(n)CF₂R³.

When G³ comprises a fluorine moiety, then G³ is selected from the group consisting of: CH(R⁶)CF₃, CH₂CF₃ and

When G⁴ comprises a fluorine moiety, then G⁴ is CH(R⁸)CF₃.

As used throughout this document, unless otherwise made clear by the context, A may be —NH—(CH₂)_(m)—CO— wherein m is 1, 2, or 3 or an alpha amino acid residue. A has a point of attachment to the compound via a nitrogen atom (N atom). The attachment point may be, for example, at the N-terminal of the amino acid residue. If the amino acid is lysine or ornithine, it is possible that either the alpha N or epsilon N of lysine or the alpha N or delta N of ornithine can be the attachment point. In the A-NHR⁹ or A-NHR¹⁰ moieties, the carboxylic acid of the amino acid residue forms an amide with the nitrogen atom of NHR⁹ or NHR¹⁰. In the A-OH moieties, the C-terminal of the amino acid residue is a carboxylic acid;

As used herein, an amino acid residue includes, but is not limited to, any of the naturally occurring alpha-, beta-, and gamma-amino carboxylic acids, including their D and L optical isomers, and the N-lower alkyl- and N-phenyl lower alkyl-derivatives of these amino acids. The amino acid residue is bonded through a nitrogen of the amino acid. The naturally occurring amino acids which can be incorporated into the present invention include, but are not limited to, alanine (ala), arginine (arg), asparagine (asn), aspartic acid (asp), cysteine (cys), cystine, glutamic acid (glu), glutamine (gin), glycine (gly), histidine (his), isoleucine (iso), leucine (leu), lysine (lys), methionine (met), ornithine (orn), phenylalanine (phe), proline (pro), serine (ser), threonine (thr), thyroxine, tryptophan (trp), tyrosine (tyr), valine (val), beta-alanine (β-ala), and gamma-aminobutyric acid (gaba). Preferred amino acid residues include proline, leucine, phenylalanine, isoleucine, alanine, gamma-amino butyric acid, valine, glycine, and phenylglycine.

All alpha-amino acids except glycine contain at least one asymmetric carbon atom. As a result, they are optically active, existing in either D or L form as a racemic mixture. Accordingly, some of the compounds of the present invention may be prepared in optically active form, or as racemic mixtures of the compounds claimed herein.

For example, the term A-OH wherein A is D-alanyl has the following structure:

The term A-NHMe wherein A is D-alanyl has the following structure

The term A-OH wherein A is —NH—(CH₂)_(m)—CO— and m is 2 has the following structure:

The term A-NHMe wherein A is epsilon-lysyl has the following structure:

The term A-NHMe wherein A is alpha-lysyl has the following structure:

As used herein, the term “alkyl,” by itself or as part of another substituent, means, unless otherwise stated, a straight or branched chain hydrocarbon radical, and can include di- and multivalent radicals, having the number of carbon atoms designated (i.e. C₁-C₁₀ or 1- to 10-membered means one to ten carbons). If not expressly indicated, the number of carbons in an alkyl group may be considered to be C₁-C₁₀ and any of the other ranges and/or specific numbers therein. Examples of hydrocarbon radicals include, but are not limited to, groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, homologs and isomers of, for example, n-pentyl, n-hexyl, n-heptyl, n-octyl, and the like. The term “alkyl,” unless otherwise noted, is not meant to include derivatives of alkyl such as “heteroalkyl.”

The term “cycloalkyl”, by themselves or in combination with other terms, represent, unless otherwise stated, cyclic versions of “alkyl”. Examples of cycloalkyl include, but are not limited to, cyclopentyl, cyclohexyl, cycloheptyl, and the like.

The terms “halo” or “halogen” by themselves or as part of another substituent, mean, unless otherwise stated, a fluorine, chlorine, bromine, or iodine atom. Additionally, terms such as “haloalkyl,” are meant to include monohaloalkyl and polyhaloalkyl. For example, the term “halo(C₁-C₄)alkyl” is mean to include, but not be limited to, trifluoromethyl, 2,2,2-trifluoroethyl, 4-chlorobutyl, 3-bromopropyl, and the like.

As used herein, the term “substituted” refers to the replacement of a hydrogen atom on a compound with a substituent group. A substituent may be a non-hydrogen atom or multiple atoms of which at least one is a non-hydrogen atom and one or more may or may not be hydrogen atoms. For example, without limitation, substituted compounds may comprise one or more substituents selected from the group consisting of: R″, OR″, NR″R′″, SR″, halogen, SiR″R′″R″″, OC(O)R″, C(O)R″, CO₂R″, CONR″R′″, NR′″C(O)₂R″, S(O)R″, S(O)₂R″, CN and NO₂. As used herein, each R″, R′″, and R″″ may be selected, independently, from the group consisting of: hydrogen, halogen, oxygen, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted alkyl, alkoxy or thioalkoxy groups, and arylalkyl groups.

“Moiety” refers to the radical of a molecule that is attached to another moiety. In particular, the term “Fluorine moiety” refers to the radical of a molecule that comprises at least one fluorine radical and/or atom.

Some embodiments of Formula I provide compounds wherein when G¹ is CH(NR¹R²)CF₃, then G³ and G⁴ are independently H or C₁-C₄ alkyl, and G² is H, C₁-C₄ alkyl or cyclopropyl.

Some embodiments of Formula I provide compounds wherein when G² is (CH₂)_(n)CF₂R³, then G¹ and G³ are independently H, C₁-C₄ alkyl, CH₂OH or CH₂NR¹R².

Some embodiments of Formula I provide compounds wherein when G² is H, then G⁴ is H or C₁-C₄ alkyl.

Some embodiments of Formula I provide compounds wherein when G³ is

then G¹ and G⁴ are independently H or C₁-C₄ alkyl.

Some embodiments of Formula I provide compounds wherein when G³ is CH₂CF₃, then G¹ is NR¹R².

Some embodiments of Formula I provide compounds wherein when G¹ is CH₂NR¹R², then G² is (CH₂)_(n)CF₂R³.

Some embodiments of Formula I provide compounds wherein when G¹ is CH(R⁷)CF₂H, then G³ and G⁴ are independently H or C₁-C₄ alkyl, and G² is C₁-C₄ alkyl or cyclopropyl.

Some embodiments of Formula I provide compounds wherein when G¹ is CH(R⁴)CF₃, then G² is C₁-C₄ alkyl or cyclopropyl; provided that when R⁴ is H or OH, then G³ is CH₂NR¹R², CH₂-A-OH, CH₂-A-NHR⁹.

Some embodiments of Formula I provide compounds wherein when G¹ is CH(R⁴)CF₃ and R⁴ is H or OH, then G⁴ is halo.

Some embodiments of Formula I provide compounds wherein when G¹ or G³ is CH₂OH, then G² is (CH₂)_(n)CF₂R³.

Some embodiments of Formula I provide compounds wherein when G¹ is NR¹R², then G³ is CH₂CF₃, G⁴ is H or C₁-C₄ alkyl and G² is C₁-C₄ alkyl or cyclopropyl.

Some embodiments of Formula I provide compounds wherein when G⁴ is CH(R⁸)CF₃, then G¹ and G³ are independently H or C₁-C₄ alkyl, and G² is hydrogen, C₁-C₄ alkyl or cyclopropyl.

Some embodiments of Formula I provide compounds wherein when G³ is CH₂-A-OH or CH₂-A-NHR, then G⁴ is H or C₁-C₄ alkyl, G² is C₁-C₄ alkyl or cyclopropyl and G¹ is CH(R⁴)CF₃ where R⁴ is H or OH.

Some embodiments of Formula I provide compounds wherein when G³ is CH₂NR¹R², and G² is C₁-C₄ alkyl or cyclopropyl, then G⁴ is H or C₁-C₄ alkyl, and G¹ is CH(R⁴)CF₃ where R⁴ is H or OH.

Some embodiments of Formula I provide compounds wherein when G¹ is CH(R⁴)CF₃ and R⁴ is H or OH, then either G³ is CH₂NR¹R² or G⁴ is halo.

Some embodiments of Formula I provide compounds wherein when G³ is CH(R⁶)CF₃, then G¹ is CH₂NR¹R² or NR¹R².

Some embodiments of Formula I provide compounds having a structure of Formula II

wherein

G¹ is H, C₁-C₄ alkyl, —CH₂OH, or —CH₂NR¹R²;

G³ is H, C₁-C₄ alkyl, —CH₂OH, or —CH₂NR¹R²;

G⁴ is H, C₁-C₄ alkyl, or halo;

R¹ and R² are either (a) two independent groups or (b) together form a single ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from the group consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, and propargyl;

R¹ and R², when together form a single ring group including the N to which they are bonded, are selected from the group consisting of: piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, and piperidinyl;

n is 1, 2 or 3; and

R³ is H, or F.

Some embodiments of Formula II provide compounds wherein n is 1.

Some embodiments of Formula II provide compounds wherein G⁴ is H.

Some embodiments of Formula II provide compounds wherein R³ is H.

Some embodiments of Formula II provide compounds wherein R³ is F.

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is methyl, R³ is F, G² is trifluoroethyl, and G¹ is H. This compound may be termed 5-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, and G¹ is methyl. This compound may be termed 3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, and G¹ is ethyl. This compound may be termed 2-ethyl-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, and G¹ is H. This compound may be termed 3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, and G¹ is CH₂OH. This compound may be termed 3-hydroxy-2-(hydroxymethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is methyl, R³ is F, G² is trifluoroethyl, and G¹ is CH₂NR¹R² wherein R¹ is methyl and R² is methyl. This compound may be termed 2-[(dimethylamino)methyl]-3-hydroxy-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is H, R³ is F, G² is trifluoroethyl, and G¹ is CH₂NR¹R² wherein R¹ is methyl and R² is methyl. This compound may be termed 2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is methyl, R³ is F, G² is trifluoroethyl, and G¹ is CH₂OH. This compound may be termed 3-hydroxy-2-(hydroxymethyl)-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is methyl, R³ is F, G² is trifluoroethyl, and G¹ is CH₂NR¹R² wherein NR¹R² is piperdinyl. This compound may be termed 3-hydroxy-6-methyl-2-(piperidin-1-ylmethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is H, R³ is H, G² is difluoroethyl, and G¹ is methyl. This compound may be termed 1-(2,2-difluoroethyl)-3-hydroxy-2-methylpyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is methyl, R³ is H, G² is difluoroethyl, and G¹ is H. This compound may termed 1-(2,2-difluoroethyl)-5-hydroxy-2-methylpyridin-4(1H)-one,

An example of a particular illustrative embodiment of Formula II is a compound in which G⁴ is H; G³ is methyl, R³ is H, G² is difluoroethyl, and G¹ is CH₂NR¹R², R¹ is methyl and R² is methyl. This compound may termed 1-(2,2-difluoroethyl)-2-[(dimethylamino)methyl]-3-hydroxy-6-methylpyridin-4(1H)-one,

Further embodiments of the compounds of Formula II are the compounds of Formula IIA:

wherein

G² is CH₂CF₂R³;

G³ is H or C₁-C₄ alkyl; and

G⁴ is H or C₁-C₄ alkyl, wherein

R³ is F or H; and

NR¹R² is morpholinyl.

An example of a particular illustrative embodiment of Formula IIA is a compound in which R³ is F, G³ is methyl, and G⁴ is H. This compound may be termed 3-hydroxy-6-methyl-2-(morpholinomethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIA is a compound in which R³ is F, G³ is H, and G⁴ is H. This compound may be termed 3-hydroxy-2-(morpholinomethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one and has the following structure:

Some embodiments of Formula I provide compounds having a structure of Formula III

wherein

G² is H, C₁-C₄ alkyl, or cyclopropyl;

G³ is H, C₁-C₄ alkyl, CH₂-A-OH, CH₂-A-NHR⁹, or CH₂NR¹R²;

G⁴ is H, C₁-C₄ alkyl, or halo;

R⁴ is selected from the group consisting of: H, OH, NR¹R², imidazole, 1,2,4-triazole, piperazine, N—C₁-C₄ alkylpiperazine, N-benzylpiperazine, N-phenylpiperazine, 2-pyridylpiperazine, and -A-NH—R¹⁰; and when R⁴ is NR¹R², imidazole, 1,2,4-triazole, piperazine, N—C₁-C₄ alkylpiperazine, N-benzylpiperazine, N-phenylpiperazine, 2-pyridylpiperazine, or -A-NH—R¹⁰, a point of attachment of R⁴ to the —CH moiety of G¹ is an N-atom of R⁴;

R¹ and R² are either (a) two independent groups or (b) together form a single ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from the group consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, and propargyl;

R¹ and R², when together form a single ring group including the N to which they are bonded, are selected from the group consisting of: piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, and piperidinyl;

A is —NH—(CH₂)_(m)—CO— or an alpha amino acid residue;

m is 1, 2 or 3; and

R⁹ and R¹⁰ are independently H, or C₁-C₄ alkyl.

Compounds of Formula III include compounds of Formula I wherein G¹ is CH(R₄)CF₃. Compounds Formula III may be further subdivided into four main subcategories, formula IIIA, formula IIIB, formula IIIC, and formula IIID.

Compounds of formula IIIA are compounds of Formula III wherein G² is C₁-C₄ alkyl, or cyclopropyl; G³ is H, or C₁-C₄ alkyl; and R⁴ is selected from the group consisting of: NR¹R², imidazole, 1,2,4-triazole, piperazine, N—C₁-C₄ alkylpiperazine, N-benzylpiperazine, N-phenylpiperazine, 2-pyridylpiperazine and -A-NH—R¹⁰.

Some embodiments of formula IIIA are compounds wherein G² is methyl.

Some embodiments of formula IIIA are compounds wherein G³ is H and G⁴ is H.

Some embodiments of formula IIIA are compounds wherein R⁴ is NR¹R².

An example of a particular illustrative embodiment of Formula IIIA is a compound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is A-NHR¹⁰, A is D-alanyl and R¹⁰ is methyl. This compound may be termed N-methyl-N²-[2,2,2-trifluoro-1-(3-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)ethyl]-D-alaninamide and has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is a compound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², R¹ is methyl, and R² is methyl. This compound may be termed 2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is a compound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², R¹ is methyl, and R² is propargyl. This compound may be termed 3-hydroxy-1-methyl-2-{2,2,2-trifluoro-1-[methyl(prop-2-yn-1-yl)amino] ethyl}pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is a compound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², R1 is H, R² is cyclopropyl. This compound may be termed 2-[1-(cyclopropylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is a compound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², R¹ is H, R² is allyl. This compound may be termed 3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(prop-2-en-1-ylamino)ethyl]pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is a compound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², NR¹R² is piperidinyl. This compound may be termed 3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIA is a compound in which G⁴ is H; G³ is H, G² is methyl, R⁴ is NR¹R², NR¹R² is N-methylpiperazinyl. This compound may be termed 3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(4-methylpiperazin-1-yl)ethyl]pyridine-4(1H)-one and has the following structure:

Compounds of formula IIIB are compounds of Formula III wherein G³ is CH₂-A-OH, CH₂-A-NHR⁹, or CH₂NR¹R²; G⁴ is H, or C₁-C₄ alkyl; and R⁴ is H, or OH.

Some embodiments of formula IIIB are compounds wherein G² is methyl.

Some embodiments of formula IIIB are compounds wherein G⁴ is H.

An example of a particular illustrative embodiment of Formula IIIB is a compound in which G⁴ is H; G³ is CH₂NR¹R², R¹ is methyl, R² is methyl, G² is methyl, and R⁴ is H. This compound may be termed 6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIB is a compound in which G⁴ is H; G³ is CH₂NR¹R², R¹ is methyl, R² is methyl, G² is methyl, and R⁴ is OH. This compound may be termed 6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIB is a compound in which G⁴ is H; G³ is CH₂-A-OH, A is L-alanyl, G² is methyl and R⁴ is OH. This compound may be termed N-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-L-alanine and has the following structure:

An example of a particular illustrative embodiment of Formula IIIB is a compound in which G⁴ is H; G³ is CH₂-A-NHR⁹, A is L-alanyl, R⁹ is methyl, G² is methyl and R⁴ is OH. This compound may be termed N²-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-N-methyl-L-alaninamide and has the following structure:

Compounds of formula IIIC are compounds of Formula III wherein G³ is H or C₁-C₄ alkyl; and G⁴ is halo.

Some embodiments of formula IIIC are compounds wherein G² is methyl.

Some embodiments of formula IIIC are compounds wherein G⁴ is chloro.

An example of a particular illustrative embodiment of Formula IIIC is a compound in which G⁴ is chloro, G³ is methyl, G² is methyl, and R⁴ is OH. This compound may be termed 3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is a compound in which G⁴ is chloro, G³ is methyl, G² is methyl, and R⁴ is H. This compound may be termed 3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is a compound in which G⁴ is chloro, G³ is methyl, G² is methyl, R⁴ is NR¹R², R¹ is methyl and R² is methyl. This compound may be termed 3-chloro-6-[1-(dimethylamino)-2,2,2-trifluoroethyl]-5-hydroxy-1,2-dimethylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is a compound in which G⁴ is chloro, G³ is H, G² is methyl, R⁴ is NR¹R², R¹ is methyl and R² is methyl. This compound may be termed 5-chloro-2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is a compound in which G⁴ is chloro, G³ is H, G² is methyl, R⁴ is NR¹R², and NR¹R² is piperidinyl. This compound may be termed 5-chloro-3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIIC is a compound in which G⁴ is chloro, G³ is H, G² is methyl, R⁴ is H. This compound may be termed 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one and has the following structure:

Compounds of Formula IIID are compounds of Formula III wherein:

G² is H, C₁-C₄ alkyl or cyclopropyl;

G³ is H or C₁-C₄ alkyl;

G⁴ is H or C₁-C₄ alkyl;

R⁴ is imidazolyl, 1,2,4-triazolyl, N-phenylpiperazinyl, N-benzylpiperazinyl, 2-pyridylpiperazinyl or morpholinyl.

Preferably, in compounds of Formula IIID, R⁴ is morpholinyl.

An example of a particular illustrative embodiment of Formula IIID is a compound in which R⁴ is morpholinyl, G² is methyl, G³ is methyl and G⁴ is H. This compound may be termed 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIID is a compound in which R⁴ is morpholinyl, G² is methyl, G³ is H and G⁴ is H. This compound may be termed 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIID is a compound in which R⁴ is N-benzylpiperazinyl, G² is methyl, G³ is methyl and G⁴ is H. This compound may be termed 2-(1-(4-benzylpiperazin-1-yl)-2,2,2-trifluoroethyl)-3-hydroxy-1,6-dimethylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIID is a compound in which R⁴ is N-phenylpiperazinyl, G² is methyl, G³ is methyl and G⁴ is H. This compound may be termed 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-(4-phenylpiperazin-1-yl)ethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IIID is a compound in which R⁴ is 2-pyridylpiperazinyl, G² is methyl, G³ is methyl and G⁴ is H. This compound may be termed 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)pyridin-4(1H)-one and has the following structure:

Some embodiments of Formula I provide compounds having a structure of Formula IV

wherein

G¹ is H, or C₁-C₄ alkyl;

G² is H, C₁-C₄ alkyl, or cyclopropyl;

G³ is H, or C₁-C₄ alkyl;

R⁸ is selected from the group consisting of: NR¹R², imidazole, 1,2,4-triazole, piperazine, N—C₁-C₄ alkylpiperazine, N-benzylpiperazine, N-phenylpiperazine, 2-pyridylpiperazine, and -A-NH—R¹⁰; a point of attachment of R⁸ to the —CH moiety of G¹ is an N-atom of R⁸;

R¹ and R² are either (a) two independent groups or (b) together form a single ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from the group consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, and propargyl;

R¹ and R², when together form a single ring group including the N to which they are bonded, are selected from the group consisting of: piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, and piperidinyl;

A is —NH—(CH₂)_(m)—CO— or an alpha amino acid residue;

m is 1, 2 or 3; and R¹⁰ is H, or C₁-C₄ alkyl.

Some embodiments of Formula IV are compounds wherein G³ is H.

Some embodiments of Formula IV are compounds wherein G¹ is methyl.

An example of a particular illustrative embodiment of Formula IV is a compound in which G³ is H; G¹ is methyl, G² is H, R⁸ is A-NHR¹⁰, A is L-alanyl, and R¹⁰ is methyl. This compound may be termed N-methyl-N²-[2,2,2-trifluoro-1-(5-hydroxy-6-methyl-4-oxo-1,4-dihydropyridin-3-yl)ethyl]-L-alaninamide and has the following structure:

An example of a particular illustrative embodiment of Formula IV is a compound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²; R¹ is methyl, and R² is methyl. This compound may be termed 5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IV is a compound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²; R¹ is H, and R² is methyl. This compound may be termed 3-hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(methylamino)ethyl]pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IV is a compound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²; NR¹R² is piperidinyl. This compound may be termed 3-hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IV is a compound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²; NR¹R² is imidazolyl. This compound may be termed 3-hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(1H-imidazol-1-yl)ethyl]pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IV is a compound in which G³ is H; G¹ is methyl, G² is methyl, R⁸ is NR¹R²; and NR¹R² is N-methylpiperazinyl. This compound may be termed 3-hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(4-methylpiperazin-1-yl)ethyl]pyridin-4(1H)-one hydrochloride and has the following structure:

Further embodiments of the compounds of Formula IV are the compounds of Formula IVA wherein:

G¹ is C₁-C₄ alkyl;

G² is H, C₁-C₄ alkyl or cyclopropyl;

G³ is H or C₁-C₄ alkyl; and

R⁸ is 1,2,4-triazolyl, N-phenylpiperazinyl, N-benzylpiperazinyl 2-pyridylpiperazinyl or morpholinyl.

Preferably, in compounds of Formula IVA, R⁸ is morpholinyl.

An example of a particular illustrative embodiment of Formula IVA is a compound in which G¹ is methyl, G² is H, G³ is H, and R⁸ is morpholinyl. This compound may be termed 3-hydroxy-2-methyl-5-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IVA is a compound in which G¹ is methyl, G² is methyl, G³ is H, and R⁸ is morpholinyl. This compound may be termed 3-hydroxy-1,2-dimethyl-5-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IVA is a compound in which G¹ is ethyl, G² is H, G³ is H, and R⁸ is N-phenylpiperazinyl. This compound may be termed 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(4-phenylpiperazin-1-yl)ethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IVA is a compound in which G¹ is ethyl, G² is H, G³ is H, and R⁸ is N-benzylpiperazinyl. This compound may be termed 5-(1-(4-benzylpiperazin-1-yl)-2,2,2-trifluoroethyl)-2-ethyl-3-hydroxypyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IVA is a compound in which G¹ is ethyl, G² is H, G³ is H, and R⁸ is 2-pyridylpiperazinyl. This compound may be termed 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)pyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula IVA is a compound in which G¹ is ethyl, G² is H, G³ is H, and R⁸ is 1,2,4-triazolyl. This compound may be termed 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(1H-1,2,4-triazol-1-yl)ethyl)pyridin-4(1H)-one and has the following structure:

Some embodiments of Formula I provide compounds having a structure of Formula V

wherein

G¹ is CH₂NR¹R², or NR¹R²;

G² is C₁-C₄ alkyl, or cyclopropyl;

G⁴ is H, or C₁-C₄ alkyl;

R⁶ is H, or OH; and

R¹ and R² are either (a) two independent groups or (b) together form a single ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from the group consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, and propargyl;

R¹ and R², when together form a single ring group including the N to which they are bonded, are selected from the group consisting of: piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, and piperidinyl.

Some embodiments of Formula V are compounds wherein G⁴ is H.

Some embodiments of Formula V are compounds wherein G² is methyl.

An example of a particular illustrative embodiment of Formula V is a compound in which G⁴ is H; R⁶ is H, G² is methyl, G¹ is NR¹R², R¹ is methyl and R² is methyl. This compound may be termed 2-(dimethylamino)-3-hydroxy-1-methyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

An example of a particular illustrative embodiment of Formula V is a compound in which G⁴ is H; R⁶ is OH, G² is methyl, G¹ is CH₂NR¹R², R¹ is methyl and R² is methyl, R¹ is methyl and R² is methyl. This compound may be termed 2-[(dimethylamino)methyl]-3-hydroxy-1-methyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one

Some embodiments of Formula I provide compounds having a structure of Formula VI:

wherein

G² is H, C₁-C₄ alkyl, or cyclopropyl;

G³ is H, or C₁-C₄ alkyl;

G⁴ is H, or C₁-C₄ alkyl;

R⁷ is selected from the group consisting of: H, OH, NR¹R², imidazolyl, 1,2,4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl, and —CH₂-A-NH—R¹⁰; and when R⁷ is NR¹R², imidazolyl, 1,2,4-triazolyl, piperazinyl, N—C₁-C₄ alkylpiperazinyl, N-benzylpiperazinyl, N-phenylpiperazinyl, 2-pyridylpiperazinyl or —CH₂-A-NH—R¹⁰, a point of attachment of R⁷ to the —CH moiety of G¹ is an N-atom of R⁷;

R¹ and R² are either (a) two independent groups or (b) together form a single ring group including the N to which they are bonded;

R¹ and R², when independent groups, are independently selected from the group consisting of: H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, allyl, and propargyl;

R¹ and R², when together form a single ring group including the N to which they are bonded, are selected from the group consisting of: piperazinyl, N—(C₁-C₄ alkyl)-substituted piperazinyl, morpholino, and piperidinyl;

A is —NH—(CH₂)_(m)—CO— or an alpha amino acid residue;

m is 1, 2 or 3; and

R¹⁰ is H, C₁-C₄ alkyl.

An example of a particular illustrative embodiment of Formula VI is a compound in which G³ is H, G⁴ is H, G² is methyl, G¹ is CH(R⁷)CF₂H, and R⁷ is hydroxy. This compound may be termed 2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

Another example of a particular illustrative embodiment of Formula VI is a compound in which G³ is H, G⁴ is H, G² is methyl, G¹ is CH(R⁷)CF₂H, and R⁷ is H. This compound may be termed 2-(2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

Further embodiments of the compounds of Formula VI are the compounds of Formula VIA wherein:

-   -   G² is H, C₁-C₄ alkyl or cyclopropyl;     -   G³ is H or C₁-C₄ alkyl; and     -   G⁴ is H or C₁-C₄ alkyl, wherein     -   R⁷ is piperazinyl, N—(C₁-C₄ alkyl) substituted-piperazinyl,         N-phenylpiperazinyl, N-benzylpiperazinyl, 2-pyridylpiperazinyl,         morpholinyl or piperidinyl.

Preferably, in compounds of Formula VIA, R⁷ is morpholinyl.

An example of a particular illustrative embodiment of Formula VIA is a compound in which R⁷ is morpholinyl, G² is methyl, G³ is H, and G⁴ is H. This compound may be termed 2-(2,2-difluoro-1-morpholinoethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula VIA is a compound in which R⁷ is 2-pyridylpiperazinyl, G² is methyl, G³ is H, and G⁴ is H. This compound may be termed 2-(2,2-difluoro-1-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula VIA is a compound in which R⁷ is N-phenylpiperazinyl, G² is methyl, G³ is H, and G⁴ is H. This compound may be termed 2-(2,2-difluoro-1-(4-phenylpiperazin-1-yl)ethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula VIA is a compound in which R⁷ is N-benzylpiperazinyl, G² is methyl, G³ is H, and G⁴ is H. This compound may be termed 2-(1-(4-benzylpiperazin-1-yl)-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula VIA is a compound in which R⁷ is piperidinyl, G² is methyl, G³ is H, and G⁴ is H. This compound may be termed 2-(2,2-difluoro-1-(piperidin-1-yl)ethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

An example of a particular illustrative embodiment of Formula VIA is a compound in which R⁷ is NR¹R wherein R¹ and R², together with N, form an N—(C₁-C₄ alkyl)-substituted piperazinyl. In a preferred embodiment, Formula VIA is a compound in which G² is methyl, G³ is H, G⁴ is H, and R⁷ is N-methylpiperazinyl. This compound may be termed 2-(1-(4-methylpiperazin-1-yl)-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and has the following structure:

Some embodiments of Formula I provide compounds having a structure of Formula VII:

wherein

G² is H, C₁-C₄ alkyl, or cyclopropyl;

G³ is H, or C₁-C₄ alkyl; and

G⁴ is H, or C₁-C₄ alkyl.

Particular illustrative embodiments of Formula VII include compounds in which G² is methyl, G³ is H, G⁴ is H, R⁵ is methyl, and R⁶ is H or OH. An example of a particular illustrative embodiment of Formula VII is a compound in which G² is methyl, G³ is H, G⁴ is H, R⁵ is methyl, and R⁶ is OH. This compound may be termed 3-hydroxy-1-methyl-2-(1,1,1-trifluoro-2-hydroxypropan-2-yl)pyridin-4(1H)-one and has the following structure:

In some embodiments, compounds of the present invention comprise a 3-hydroxypyridin-4-one moiety having a halo group, attached to the C5 position of the ring (G⁴ is halo), and a trifluoroethyl moiety, at the G¹ or G² or G³ position. In some of these embodiments, the halo group is a chloro group.

The following Schemes 1-9 depict examples of methods that can be used for the preparation of compounds of the Formulas I, II, III, IV, V, VI, and VII. All of the starting materials are prepared by procedures described in these schemes, by procedures well known to one of ordinary skill in organic chemistry or can be obtained commercially. All of the final compounds of the present invention may be prepared by procedures described in these schemes or by procedures analogous thereto.

The compounds of Formula I wherein G²=—(CH₂)_(n)CF₂R³ can be prepared by the method as shown in Scheme 1, or by the methods given in the examples or by analogous methods. As shown in Scheme 1, compound (1a) wherein G¹ is H or C₁-C₄ alkyl, G³ is H or C₁-C₄ alkyl, G⁴ is H or C₁-C₄ alkyl, may be treated with sodium hydroxide and benzyl bromide or benzyl chloride to give the compound (1b). The amine insertion with compound (1b) may be conducted with trifluoroethylamine hydrochloride and an organic base such as pyridine in an inert solvent to give compound (1c) wherein n is 1 and R³ is F, which may be deprotected either by hydrolysis with hydrochloric acid solution or by catalytic hydrogenation over 10% Pd/C to give a compound of formula II. Compound of formula II is a compound of Formula I wherein R³ is F, and n is 1.

As an illustrative example, the compounds of Formula I wherein G¹ is H, G³ is H, G⁴ is H, n is 1, R³ is F can be prepared by the method shown in Scheme 2.

Compound (2a) may be reacted with CF₂R³CH₂NH₂ in water to give a compound (2b), which upon heating in inert organic solvent such as dimethylformamide, affords the compound (2c), which may be deprotected with catalytic hydrogenation using hydrogen, catalytic palladium on charcoal to give a compound (2d), which is compound of Formula II wherein n is 1, G¹ is H, G³ is H, G⁴ is H. Compound (2d) is also a compound of formula I wherein G¹ is H, G³ is H, G⁴ is H, n is 1, G² is —CH₂CF₂R³.

The compounds of Formula I wherein n is 1, G² is CH₂CF₂R³, G¹ is CH₂NR¹R², CH₂OH, or a compound of formula II wherein G¹ is CH₂OH or CH₂NR¹R² are prepared by the method as shown in Scheme 3.

Compound (3a) may be reacted with formaldehyde and sodium hydroxide to give compound (3b). Reaction of compound (3b) with thionyl chloride in an inert solvent such as acetonitrile affords the chloro compound (3c), which may be quenched with an amine R¹R²NH to give the compound of Formula (3d), which is a compound of Formula I when G¹ is CH₂NR¹R². The compound may be isolated by conventional means. Alternatively, when n=1, compound (3a) may be reacted directly with bis-(dimethylamino)methane to give the compound (3d), which is a compound of Formula I wherein G¹ is CH₂N(CH₃)₂.

The compounds of Formula I wherein G¹ is CH(R⁴)CF₃, R⁴ is NR¹R², OH, H or the compounds of Formula III wherein R⁴ is NR¹R², OH, H; G² is H, C₁-C₄ alkyl; G³ is H, C₁-C₄ alkyl; G⁴ is H, C₁-C₄ alkyl, halo; may be prepared by the method as shown in Scheme 4. For illustration purposes, the scheme shows the synthesis of a compound of Formula I or IIIA or IIIC wherein G³ is H.

Compound (4a) may be reacted with sodium hypochlorite in 2N NaOH to give the chloro derivative (4b), which may then be reacted with potassium carbonate and methyl iodide in dimethylformamide to give the N-methyl compound (4c). TEMPO oxidation in an inert solvent such as acetone affords the carboxylic acid (4d). Acid deprotection and decarboxylation with 6N hydrochloric acid affords the starting material (4e). Compound (4e) may be reacted with CF₃CH(OCH₃)OH to give the diol (4f). Treatment of thionyl chloride and pyridine yields the chloride (4g). Upon reacting compound (4g) with sodium borohydride, compound (4h) may be formed. Compound (4i) is obtained from the quenching of the chloride (4g) with R¹R²NH.

Compound (4i) is a compound of Formula I wherein G¹ is CH(R⁴)CF₃, R⁴ is NR¹R² wherein R¹, R² are methyl, G² is methyl, G³ is H, and G⁴ is chloro. It is also a compound of formula III wherein R⁴ is NR¹R² wherein R¹, R² are methyl, G² is methyl, G³ is H, and G⁴ is chloro.

Compound (4h) is a compound of Formula I wherein G¹ is CH(R⁴)CF₃, R⁴ is H, G² is methyl, G³ is H, G⁴ is chloro. It is also a compound of formula III wherein R⁴ is H, G² is methyl, G³ is H, G⁴ is chloro.

Compound (4f) is a compound of Formula I wherein G¹ is CH(R⁴)CF₃, R⁴ is OH, G² is methyl, G³ is H, G⁴ is chloro. It is also a compound of formula III wherein R⁴ is OH, G² is methyl, G³ is H, G⁴ is chloro.

The compound of Formula I wherein G⁴ is CH(R⁸)CF₃, R⁸ is NR¹R², G³ is H, G¹ is C₁-C₄ alkyl, G² is C₁-C₄ alkyl or the compound of formula IV wherein R⁸ is NR¹R², G³ is H, G¹ is methyl, G² is methyl may be prepared according to the representative procedures as outline in Scheme 5 below:

Compound (5c) may be prepared according to the procedure outlined in WO20080242706. Reaction of compound (5c) with thionyl chloride gives (5d) which may be quenched with an amine R¹R²NH to give compound (5e). Compound (5e) is a compound of Formula I wherein G⁴=CH(R⁸)CF₃, R⁸ is NR¹R², G³ is H, G¹ is methyl, G² is methyl. It is also a compound formula IV wherein R⁸ is NR¹R², G³ is H, G¹ is methyl, G²=methyl. When R¹ is methyl, R² is methyl, compound (5e) has the chemical name 5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one.

A compound of Formula I wherein G¹ is CH(R⁴)CF₃, R⁴ is H or OH, G² is C₁-C₄ alkyl, G³ is CH₂NR¹R², G⁴ is H or a compound of formula IIIB wherein R⁴ is H or OH, G² is methyl, G³ is CH₂NMe₂, G⁴ is H may be prepared according to the representative procedures as outline in Scheme 6 below:

Alcohol (6a) may be converted to the chloro compound (6b) with thionyl chloride. Upon quenching with dimethylamine, compound (6c) is formed, which may be deprotected by catalytic hydrogenation with palladium on charcoal to give compound (6d). Reaction of compound (6d) with CF₃CH(OH)OCH₃ and potassium carbonate affords the diol (6e), which reacts with thionyl chloride to give the compound (6f). Reduction of the chloro compound with catalytic hydrogenation yields the compound (6g). Compound (6e) is a compound of Formula I wherein G⁴ is H, G³ is CH₂NR¹R², R¹ is methyl, R² is methyl, G² is methyl, G¹ is CH(R⁴)CF₃, R⁴ is OH. It is also a compound of formula IIIB wherein G⁴ is H, G³ is CH₂NR¹R², R¹ is methyl, R² is methyl, G² is methyl, R⁴ is OH. Compound (6e) has the chemical name 6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one.

Compound (6g) is a compound of Formula I wherein G⁴ is H, G³ is CH₂NR¹R², R¹ is methyl, R² is methyl, G² is methyl, G¹ is CH(R⁴)CF₃, R⁴ is H. It is also a compound of formula IIIB wherein G⁴=H, G³=CH₂NR¹R², R¹ is methyl, R² is methyl, G² is methyl, G¹R⁴ is H. Compound (6e) has the chemical name 6-[(dimethylamino)methyl]-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one.

A compound of Formula I wherein G³ is H or C₁-C₄ alkyl; G⁴ is H, or C₁-C₄ alkyl; G¹ is CH(R⁷)CF₂H, or a compound of formula VI wherein G³ is H or C₁-C₄ alkyl; G⁴ is H, or C₁-C₄ alkyl; R⁷ is H, OH, NR¹R² may be prepared according to the representative procedures as outline in Scheme 7 below:

Compound (7a) may be reacted with difluoroacetaldehyde ethyl hemiacetal and potassium carbonate to give the compound of Formula (7b). This intermediate may be converted to compounds (7e) and (7d) in a similar manner as described for the conversion of compound (4f) to (4h) and (4i) (Scheme 4). (7b) is a compound of Formula I wherein G¹ is CH(R⁷)CF₂H, R⁷ is OH or a compound of formula VI wherein R⁷ is OH. (7e) is a compound of Formula I wherein R⁷ is H, or a compound of formula VI wherein R⁷ is H and (7d) is a compound of Formula I wherein G¹ is CH(R⁷)CF₂H, R⁷ is NR¹R² or a compound of formula VI wherein R⁷ is NR¹R². For example, when G² is methyl, G³ is H, G⁴ is H in scheme 1, the compound (7e) is 2-(2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one and the compound (7b) is 2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one.

The compound of Formula I wherein G³ is CH(R⁶)CF₃, R⁶ is H, G¹ is NR¹R² or a compound of formula V wherein R⁶ is H, G³ is CH₂CF₃, G¹ is NR¹R² may be prepared according to the representative procedures as outline in Scheme 8 below:

Compound (8a) wherein G² is C₁-C₄ alkyl, G⁴ is H may be first reacted with thionyl chloride in an inert solvent. Quenching the reaction with an amine R¹R²NH affords the compound (8b). The structure of (8b) may be confirmed by NMR and MS spectroscopy. The compound of Formula (8b) is a compound of Formula I wherein G² is C₁-C₄ alkyl, G⁴ is H, or C₁-C₄ alkyl, R⁶ is H; or a compound of formula V wherein R⁶ is H, G² is C₁-C₄ alkyl, G¹ is NR¹R², G⁴ is H. For example, the compound 5-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one is a compound (8a) wherein G⁴ is H, G² is methyl. Compound (8a) can be converted to 2-(dimethylamino)-3-hydroxy-1-methyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one, a compound of (8b) wherein R¹ is methyl, R² is methyl, G² is methyl, G⁴ is hydrogen with dimethylamine according to the method described in Scheme 8.

Compound of Formula I wherein G¹ is C(R⁵)(R⁶)CF₃, R⁵ is C₁-C₄ alkyl, R⁶ is OH or a compound of formula VII wherein R⁵ is C₁-C₄ alkyl, R⁶ is OH may be prepared according to the representative procedures as shown in Scheme 9 below:

Compound (9a) may be first reacted with Dess-Martin oxidation reagent to give compound 9b, which may be reacted with the Grignard reagent R⁵—MgCl or R⁵—MgBr to give compound 9c. Catalytic hydrogenation of 13 with palladium on charcoal affords compound 9d, which is a compound of Formula I when R⁵ is C₁-C₄ alkyl, R⁶ is OH. For example, in when G² is methyl, G³ is H, G⁴ is H, R⁵ is methyl in Scheme 9, the product (9d) is the compound 3-hydroxy-1-methyl-2-(1,1,1-trifluoro-2-hydroxypropan-2-yl)pyridin-4(1H)-one.

Many compounds of this invention or for use in this invention may be formed as salts. In such cases, pharmaceutical compositions in accordance with this invention may comprise a salt of such a compound, preferably a physiologically acceptable salt, which are known in the art. Pharmaceutical preparations will typically comprise one or more carriers acceptable for the mode of administration of the preparation, be it by injection, inhalation, topical administration, lavage, or other modes suitable for the selected treatment. Suitable carriers are those known in the art for use in such modes of administration.

Suitable pharmaceutical compositions may be formulated by means known in the art and their mode of administration and dose determined by the skilled practitioner. For parenteral administration, a compound may be dissolved in sterile water or saline or a pharmaceutically acceptable vehicle used for administration of non-water soluble compounds such as those used for vitamin K. For enteral administration, the compound may be administered in a tablet, capsule or dissolved in liquid form. The tablet or capsule may be enteric coated, or in a formulation for sustained release. Many suitable formulations are known, including, polymeric or protein microparticles encapsulating a compound to be released, ointments, pastes, gels, hydrogels, or solutions which can be used topically or locally to administer a compound. A sustained release patch or implant may be employed to provide release over a prolonged period of time. Many techniques known to one of skill in the art are described in Remington: the Science & Practice of Pharmacy by Alfonso Gennaro, 20^(th) ed., Lippencott Williams & Wilkins, (2000). Formulations for parenteral administration may, for example, contain excipients, polyalkylene glycols such as polyethylene glycol, oils of vegetable origin, or hydrogenated naphthalenes. Biocompatible, biodegradable lactide polymer, lactide/glycolide copolymer, or polyoxyethylene-polyoxypropylene copolymers may be used to control the release of the compounds. Other potentially useful parenteral delivery systems for modulatory compounds include ethylene-vinyl acetate copolymer particles, osmotic pumps, implantable infusion systems, and liposomes. Formulations for inhalation may contain excipients, for example, lactose, or may be aqueous solutions containing, for example, polyoxyethylene-9-lauryl ether, glycocholate and deoxycholate, or may be oily solutions for administration in the form of nasal drops, or as a gel.

Compounds or pharmaceutical compositions in accordance with this invention or for use in this invention may be administered by means of a medical device or appliance such as an implant, graft, prosthesis, stent, etc. Also, implants may be devised which are intended to contain and release such compounds or compositions. An example would be an implant made of a polymeric material adapted to release the compound over a period of time.

An “effective amount” of a pharmaceutical composition according to the invention includes a therapeutically effective amount or a prophylactically effective amount. A “therapeutically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic result, such as improved iron distribution or reduced levels of toxic iron. A therapeutically effective amount of a compound may vary according to factors such as the disease state, age, sex, and weight of the subject, and the ability of the compound to elicit a desired response in the subject. Dosage regimens may be adjusted to provide the optimum therapeutic response. A therapeutically effective amount is also one in which any toxic or detrimental effects of the compound are outweighed by the therapeutically beneficial effects. A “prophylactically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired prophylactic result, such as such as improved iron distribution or reduced levels of toxic iron. Typically, a prophylactic dose is used in subjects prior to or at an earlier stage of disease, so that a prophylactically effective amount may be less than a therapeutically effective amount.

It is to be noted that dosage values may vary with the severity of the condition to be alleviated. For any particular subject, specific dosage regimens may be adjusted over time according to the individual need and the professional judgement of the person administering or supervising the administration of the compositions. Dosage ranges set forth herein are exemplary only and do not limit the dosage ranges that may be selected by medical practitioners. The amount of active compound(s) in the composition may vary according to factors such as the disease state, age, sex, and weight of the subject. Dosage regimens may be adjusted to provide the optimum therapeutic response. For example, a single bolus may be administered, several divided doses may be administered over time or the dose may be proportionally reduced or increased as indicated by the exigencies of the therapeutic situation. It may be advantageous to formulate parenteral compositions in dosage unit form for ease of administration and uniformity of dosage.

In general, compounds of the invention should be used without causing substantial toxicity. Toxicity of the compounds of the invention can be determined using standard techniques, for example, by testing in cell cultures or experimental animals and determining the therapeutic index, i.e., the ratio between the LD50 (the dose lethal to 50% of the population) and the LD100 (the dose lethal to 100% of the population). In some circumstances however, such as in severe disease conditions, it may be necessary to administer substantial excesses of the compositions.

As used herein, a “subject” may be a human, non-human primate, rat, mouse, cow, horse, pig, sheep, goat, dog, cat, etc. The subject may be suspected of having or at risk for having a medical condition related to a toxic concentration of iron. The medical condition related to a toxic concentration of iron may be selected from the group consisting of: cancer, pulmonary disease, progressive kidney disease and Friedreich's ataxia. Diagnostic methods for various medical conditions related to a toxic concentration of iron and the clinical delineation of various medical conditions related to a toxic concentration of iron and their diagnoses are known to those of ordinary skill in the art.

An important property of iron is its ability to donate and accept an electron readily between the ferrous (Fe²⁺) and ferric (Fe³⁺) species. This can be a liability as iron can play a critical role in both the Fenton and the Haber-Weiss reactions in catalyzing the production of hydroxyl radicals. Thus, in conditions wherein the reduction of Fe(III) to Fe(II) is facilitated, the generation of these active oxygen species (hydroxyl radical) can cause considerable damage to biomolecules in the living system that include cellular membranes, proteins and DNA. Fe³⁺+O₂ ⁻→Fe²⁺+O₂ (reduction of metal) Fe²⁺+H₂O₂→Fe³⁺+OH⁻+OH (Fenton reaction) H₂O₂+O₂ ⁻→O₂+OH⁻+OH (Haber-Weiss cycle)

Iron chelators can either inhibit or facilitate the participation of iron in the Fenton and Haber-Weiss reactions that produce toxic oxygen radicals. Since certain iron chelators can potentially promote Fe³⁺ reduction, early evaluations on whether the chelator can promote, prevent, or has no effect on Fe³⁺ reduction are essential.

There are several quintessential methods and chemical models that have been used to study the capacity of the chelators to restrict the participation of iron in radical generating reactions via the indirect observation of radical formation (Dean R T and Nicholson P (1994) Free Radical Res 20:83-101 and Gutteridge J M (1990) Free Radical Res Commun 9:119-125). The use of cyclic voltammetry, and benzoic acid hydroxylation assay in screening the compounds of formula I are illustrated in the examples 30 and 31, respectively.

The neuroprotective effect of compounds of formula I is demonstrated in the hydrogen peroxide induced apoptosis in SH-SY5Y neuroblastoma cells assay in example 32A. The protective effective of compounds of formula I against endogenously produced Aβ toxicity is shown in example 32B. Cytotoxicity was also induced by the dopaminergic neurotoxin MPP⁺ on SV-NRA cells. The neuroprotective action of selected compounds of formula I is further demonstrated in MPP⁺ treated SV-NRA cells in Example 33 below.

In-vivo pharmacokinetic (PK) and blood brain barrier (BBB) studies were conducted in male Sprague-Dawley rats using cassette dosing via oral administration. The topic of cassette dosing has been reviewed by Manitpisitkul, P. and White, R. E. (August 2004), Drug Discovery, Vol 9. No. 15, pp. 652-658. The results are summarized in the Table below:

Oral Cassette Dosing Studies of a compound of formula I in male Sprague-Dawley rats, AUCs is normalized to 1 mg/kg dose AUC AUC brain* AUC plasma* brain/AUC CL Cpd (ug-h/mL) (ug-h/mL) plasma (L/h-kg) Apo6995 0.30 0.26 1.2 3.89 Apo7030 0.59 (cal.) 0.59 1.00 1.68 Apo7041 0.45 0.60 0.75 1.67 Apo7080 0.7  0.92 0.76 1.09 Apo7067 0.74 0.5 1.50 2.00 Apo7056 0.77 1.38 0.56 0.72 Clioquinol  0.042 0.028 1.5 3.52 List of Compounds of Formula I Tested in Cassette Dosing BBB Studies

Cpd G⁴ G³ G² G¹ Apo6995 H H CF₃CH₂ CH₃ Apo7030 H H CF₃CH₂ CH₃CH₂ Apo7041 H H CH₃ CF₃CH(NMe₂)— Apo7080 H H CH₃ CF₂HCH₂— Apo7067 H H CF₃CH₂ Me₂NCH₂— Apo7056 CF₃CH(NHMe)— H CH₃ CH₃

It is generally accepted that 1,2-dimethyl-3-hydroxypyrid-4-one and its alkyl derivatives are bidentate ligands (Ls) and react with Fe(III) to form neutral 1:3 chelates. In the speciation plot as shown in FIG. 4, the percentage of FeL₃ species is close to 100 at pH 7.4 when deferiprone is used as ligand. The resulting Fe chelate (FeL₃) is not redox active, as evidenced by cyclic voltammetry analysis. However, if the pH is lowered to 6.0, a mixture of FeL₂ ⁺ and FeL₃ species are now present in solution. Deferiprone (1,2-dimethyl-3-hydroxypyrid-4-one) is effective on the removal of Fe(III) at pH>7.2 at physiological conditions, but at a lower pH, deferiprone and its alkyl derivatives are significantly less effective.

Hider et al. (J. Pharm. Pharmacol. 2000, 52, 263-273; European Journal of Medicinal Chemistry 2008, 42, 1035-1047) reported the use of alkylamino derivatives of 3-hydroxypyridin-4-ones. Two speciation plots are illustrated with two different concentration of 2-ethyl-3-hydroxy-1-[2-(piperidin-1-yl)ethyl]pyridin-4(1H)-one [L] at 1×10⁻⁵ M and 7×10⁻⁴ M, respectively, while maintaining the concentration of [Fe] fixed at 1×10⁻⁶M. The FeL₃ chelate has a broader stability profile only at pH >5 and above, and when [L] is 7×10⁻⁴ M (FIG. 9 of J. Pharm. Pharmacol. 2000, 52, 271). However, at a concentration of [L] at 1×10⁻⁵ M, the FeL₃ stability profile is very similar to that of Fe-deferiprone complex.

Selected amino compounds of this invention such as Apo7041 have FeL₃ chelate stability that extends from pH 5 and above. Analysis of photospectroscopic data of the Fe chelate shows that the fluorinated 3-hydroxypyridin-4-one with weak base amino group is a stronger proton acceptor than the oxygen atom in the Fe—O bond of the chelate. Between pH 5 to 7.2, the Fe(III) is trapped as a ferric chelate in the form of FeL₃ and FeL₃H. The Apo7041 speciation plot in FIG. 5 showed that no FeL₂ is present at above pH 5.0. In addition, the ligand concentration [L] does not affect the outcome of speciation plot in this chemical study.

The number of weak basic amines available as proton acceptor is three in the ferric chelate. Before the scission of the Fe—O bond of the 1:3 chelate, all three amino groups have to be protonated. The characteristic of this compound behaving as an internal proton sink results in an improvement in the chelate stability at low pH, which offers clear advantage over the neutral 3-hydroxypyridin-4-ones such as deferiprone. FIG. 6 and FIG. 7 outline the comparison of the neutral and basic amine chelates. Upon dropping the pH to around 5.0, a significant amount of FeL₃ decomposed to give FeL₂ via the cleavage of the Fe—O bond when L is a neutral ligand. However, the chelates from the basic amines derivatives of formula I in this invention are stable at lower pHs.

Example 54 illustrates the speciation distribution of several amino fluorinated derivatives of 3-hydroxypyridin-4-(1H)-ones of the invention. The speciation plot (distribution of ferric chelate species) of two compounds of formula I (Apo7067 and Apo7323) at pH 7.4 is provided in the following table.

Apo7067 Apo7323 % at % at Structure Apo7067 pH Structure Apo7323 pH

pKas shown 7.4

pKas shown 7.4

Species 130 Fe(Apo7067)₃ 12.3

Species 130 Fe(Apo7323)₃ 96.9

Species 131 Fe(Apo7067)₃H 61.8

Species 131 Fe(Apo7323)₃H 3.1

Species 132 Fe(Apo7067)₃H₂ 24.6

Species 132 Fe(Apo7323)₃H₂ 0.0

Species 133 Fe(Apo7067)₃H₃ 1.2

Species 133 Fe(Apo7323)₃H₃ 0.0

As shown in the table, the amine pKa of Apo7067 and Apo7323 is 6.1 and 4.2, respectively. This difference in pKa results in different speciation outcomes at pH 7.4 since the stage of protonation of the ferric chelate is dependent on the pKa of the amino group. At pH 7.4, for Apo7067, which has an amine pKa of 6.1, the charged species Fe(Apo7067)₃H and Fe(Apo7067)₃H₂ are predominant, with the uncharged form, Fe(Apo7067)₃, representing only about 12% of the chelate population. However, for Apo7323, which has an amine pKa of 4.2, Fe(Apo7323)₃, the uncharged chelate, is the predominant at pH 7.4.

Thus, depending on the therapeutic utility required, the amino pKa of the compounds of the invention can be used to produce a ferric chelate that is either charged or uncharged at pH 7.4. In the case of Apo7323, about 97% of the ferric chelate is uncharged at pH 7.4, which will facilitate the removal of complexed iron from cells. This property is very close to Fe-deferiprone ferric chelate wherein the chelate is uncharged at pH 7.4. However, compounds of the present invention have increased lipophilicty when compared to deferiprone, which allows them to more easily penetrate the blood-brain barrier. Compounds of the invention containing an amine group, which deferiprone lacks, also allow the compounds to accumulate in the acidic compartments of cells prior to iron chelation.

Amine compounds of the invention capable of forming charged ferric chelates at pH 7.4 may be used for the treatment of kidney diseases involving a localized toxic concentration of iron, wherein the amine compound can react with iron to form a ferric chelate that is easily excreted as a charged chelate species in the urine.

Deferiprone undergoes Phase II metabolism resulting in extensive glucuronidation at the C3 oxygen of the 3-hydroxypyridin-4-one skeleton. Therefore, a high oral dose of deferiprone is required to achieve therapeutic effect. Selected compounds of this invention are designed specifically to block the C3 oxygen from glucuronidation by the introduction of a bulky C3 or C5 trifluroroethyl moiety substituted with an amine derivative. In modeling studies, a simple trifluoroethyl group has the same steric bulk as an isopropyl group. For example, the steric bulk of a 1-dimethylamino-2-trifluoroethyl substituent may prevent the C3 O-glucuronidation without affecting the formation of the ferric chelate FeL₃. The 3D modeling of the compound Fe(Apo7041)₃ is shown in FIG. 8.

Cyclic voltammetry experiments show that a stable Fe(Apo7041)₃ is formed with E_(1/2)=−731 mV (FIG. 2). The data showed that the Fe(Apo7041)₃ is non redox active and is a stable chemical entity. The cumulative log β₁₃₀ value of Apo7041 for Fe(III) is 38.8 (Table 29B in example 29B), which is relatively higher than that of deferiprone with a value of 37.24 (Table 1). Unlike other amine derivatives of 3-hydroxypyridin-4-on reported by Hider et al., the pKa of the C2-amino moiety of Apo7041 is 3.5 in 0.1 M aqueous NaCl. Thus, at pH 3.5, the protonated form and the non-protonated form of the amine exist in a 1:1 ratio. With an incremental unit increase in pH, there will be significantly more free base present in the media.

Selected amino derivatives of this invention have better metal selectivity when compared to deferiprone. The metal binding properties of Apo7041 are compared to those of deferiprone in Table 1. For example, the cumulative log β₁₂₀ for Zn(II) and Cu(II) are 13.2 and 17.3, respectively, for Apo7041, which are 2 to 3 orders of magnitude lower as compared to those for deferiprone at 15.0 and 20.5, respectively, in 0.1M aqueous NaCl/MeOH, 1/1, v/v. Thus, the amine derivatives of this invention are selective for Fe(III). The ranking according to binding affinities are Fe(III)>>Cu(II)>>Zn(II).

TABLE 1 Comparison of the metal binding properties of the amino compound Apo7041 and deferiprone.^(a,b) Properties

pKa^(a) pKa₁ = 10.6 pKa₁ = 10.1 pKa₂ = 4.0 pKa₂ = 3.2 pKa₃ = 2.0 Cu²⁺ chelation^(a) Logβ₁ = 10.8 Logβ₁₁₁ = 14.1 Logβ₂ = 20.5 Logβ₁₂₂ = 27.9 pCu²⁺ = 9.9 Logβ₁₂₁ = 23.0 Logβ₁₂₀ = 17.3 pCu²⁺ = 7.7 Zn²⁺ chelation^(a) Logβ₁ = 8.1 Logβ₁₁₁ = 13.1 Logβ₂ = 15.0 Logβ₁₂₁ = 19.6 pZn²⁺ = 6.3 Logβ₁₂₀ = 13.2 pZn²⁺ = 6.0 Fe³⁺ chelation^(b) pKa₁ = 9.92 pFe³⁺ = 23.4 pKa₂ = 3.55 Logβ₁₁₀ = 14.85 Logβ₁₂₀ = 27.25 Logβ₁₃₀ = 37.24 pFe³⁺ = 20.2 ^(a)Except for Fe³⁺, the pKas and log β values were determined in 0.1M aqueous NaCl/MeOH, 1/1, v/v, mixture. ^(b)For Fe³⁺, the pKas and log β values were determined in 0.1M aqueous NaCl. For details, see Example 29B.

A utility of compounds of this invention may be in the treatment of patients with kidney disease in which the presence of iron is detected in the urine. The detection of both protein content and free iron in urine as a possible method of monitoring kidney disease has been reported in U.S. Pat. No. 6,906,052.

One biological function of the kidney is to retain protein. The term “proteinuria” means the presence of an excess of serum proteins in the urine, and may be a sign of renal (kidney) damage. Injury to the glomerulus or tubule or pancreas can adversely affect the ability of the kidney to retain protein. In the urine of animals with nephritic syndrome, the pH of the urine can vary from pH 5.2 to 7.8. Animal experiments have shown that iron is bound to transferrin at a pH of 6.05. When the pH drops to below 6.0, there is a marked increase in unbound iron. Iron dissociated from transferrin is able to cause potentially serious free radical damage to the kidney. Small low molecular chelator such as deferiprone has been used to chelate the free iron as a possible treatment therapy.

Cooper et al. reported the urinary iron speciation (American Journal of Kidney Diseases, 25, 1995, 314-319) in nephrotic syndrome where iron is presented to the tubule fluid in a nonreactive form in association with transferrin as a result of the glomerular protein leak. In nephritic rats, iron remains bound to transferrin throughout the nephron and is excreted as such in the urine at alkaline pH. As urine pH decreases below 6, iron starts to dissociate from transferrin. As mentioned earlier, free iron is redox active and may cause further progression of the renal diseases.

A weak base compound can accumulate at an acidic compartment to exert its biological action. Neutral compounds and strong bases do not accumulate in such a manner. For example, the antisecretory agent omeprazole is a weak base that concentrates in the acidic compartment of the parietal cell to exert its pharmacological properties. The amino derivatives of 3-hydroxypyridin-4-one of this invention favor the accumulation at sites wherein the compartment is slightly acidic. One such example may be the nephron of kidney disease patients.

The amino derivatives of 3-hydroxypyridin-4-one of this invention have at least one of a number of properties: (a) they are weak amines that can accumulate in the acidic compartment of a biological system; (b) the 1:3 FeL₃ chelates are stable at lower pH between 5 and 7.2 when compared to the chelate from the neutral alkyl derivatives of 3-hydroxypyridin-4-one such as deferiprone; (c) they are non-redox active as evidenced by the cyclic voltammetric study; (d) they carry a bulky substituent at the C2 or C5 position that may block the glucuronidation of the C3-OH, and may thus require a lower therapeutic dose of drug; (e) higher clearance rate than deferiprone in cassette dosing pharmacokinetic studies. Thus compounds of this invention may have a propensity to undergo urinary excretion, and it is understood that the relevant site of free iron for renal disease patients is the kidney.

Another possible utility of the amino compounds of this invention is in the treatment of cancer and inflammatory lung disorders. Buss et al. reviewed the role of iron chelation in cancer therapy (Current Medicinal Chemistry, 2003, 12, 1021-1034). DNA damage after oxidative stress involves a transition metal such as iron. Lysosomes contain a comparatively high concentration of redox-active iron, which is mainly generated from the degradation of iron-containing proteins. The acidic compartment of the lysosome further facilitates iron catalysed oxidative reactions (Kurz et al., Biochem. J. (2004) 378, 1039-1045). The iron chelator DFO has been reported to inhibit DNA synthesis and cell proliferation. DFO is a weak base with a free amino terminal and can accumulate in the lysosome to exert its chelation mechanism. Unfortunately, DFO is a large peptide hexadentate chelator and will not easily penetrate the cell. The amine compounds of this invention are low molecular weight compounds. The weak basic nature of the compound and its lipophilic character allows the compound to accumulate in the acidic compartment of the lysosomes.

Richardson et al. reported that the most important cellular pool of redox-active iron may exist within lysosomes, making the organelles vulnerable to oxidative stress (Expert Opinion on Investigational Drugs, August 2005, Vol. 14, No. 8, Pages 997-1008). Oxidative stress will result in tissue damage. As a result, iron-chelating therapy that targets the lysosome may be a possible treatment strategy for inflammatory pulmonary diseases. Weak base cell-permeable low molecular weight iron chelators may accumulate in the acidic compartment of lysosomes, and may therefore be more effective than desferrioxamine as cytoprotective agents. Therefore, another possible utility for the weak bases of this invention is the use of such compounds for the treatment of inflammatory pulmonary diseases.

Most of the non-amino N¹-trifluoroethyl or C²-difluoroethyl derivatives of 3-hydroxypyridin-4-one of this invention are intermediates for the synthesis of the amino derivatives. In addition, compounds of formula I wherein G¹ is C₁-C₆ alkyl and G² is trifluoroethyl or G¹ is difluoroethyl and G² is C₁-C₆ alkyl are examples of derivatives of 3-hydroxypyridin-4-ones without an amine side chain. Some of these neutral derivatives of 3-hydroxypyridin-4-one of this invention are significantly more lipophilic than deferiprone. In BBB cassette dosing studies, they display higher brain to plasma concentration ratio, making them more favorable for accumulation in the brain. These compounds may be targeted for accumulation in the brain and used towards treatment of diseases such as Friedreich's ataxia wherein the chelator is used to reduce ataxia and cerebellar iron in the brain.

All compounds of this invention have specificity for the complexation of Fe(III) with favorable phenolic C3 OH pKas and pFe(III)>19, a smooth 1:3 ferric chelate formation as evident by Job's plot, and a D_(7.4) value>0.1. Further, the metal selectivity studies show that the compound does not chelate essential metals such as calcium, magnesium and zinc.

Although various embodiments of the invention are disclosed herein, many adaptations and modifications may be made within the scope of the invention in accordance with the common general knowledge of those skilled in this art. Such modifications include the substitution of known equivalents for any aspect of the invention in order to achieve the same result in substantially the same way. Numeric ranges are inclusive of the numbers defining the range. The word “comprising” is used herein as an open-ended term, substantially equivalent to the phrase “including, but not limited to”, and the word “comprises” has a corresponding meaning. As used herein, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a thing” includes more than one such thing. Citation of references herein is not an admission that such references are prior art to the present invention. Any priority document(s) are incorporated herein by reference as if each individual priority document were specifically and individually indicated to be incorporated by reference herein and as though fully set forth herein. The invention includes all embodiments and variations substantially as hereinbefore described and with reference to the examples and drawings.

Various alternative embodiments and examples of the invention are described herein. These embodiments and examples are illustrative and should not be construed as limiting the scope of the invention.

Example 1 Preparation of 3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

(a) Preparation of 3-(benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

3-(Benzyloxy)-2-methyl-4H-pyran-4-one (1.00 g, 4.6 mmol) was mixed with trifluoroethylamine hydrochloride (1.35 g, 10.0 mmol) in pyridine (10 mL). The reaction mixture was heated in a sealed flask at 75° C. for 5 hours. The mixture was concentrated and the residue was purified by column chromatography on silica gel with 5% methanol in ethyl acetate as eluant to give 3-(benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.82 mg) as beige solid. Yield=60%; ¹H NMR (CDCl₃, 90 MHz) δ (ppm): 7.02-7.58 (m, 6H), 6.42 (d, J=7.5 Hz, 1H), 5.20 (s, 2H), 4.30 (q, J=8.3 Hz, 2H) and 2.10 (s, 3H).

(b) Preparation of 3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

3-(Benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (820 mg, 2.8 mmol) was mixed with 10% palladium on charcoal (wet, 84 mg) in methanol (20 mL). The mixture was stirred at room temperature under hydrogen at 30 psi in a Parr apparatus for 35 minutes. The mixture was filtered through Celite™ and the filtrate was concentrated. The residue was triturated with ether to give 3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (511 mg) as off-white solid. Yield=89%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 7.60 (d, J=7.4 Hz, 1H), 6.20 (d, J=7.4 Hz, 1H), 4.99 (q, J=8.8 Hz, 2H) and 2.29 (s, 3H).

Example 2 Preparation of 3-hydroxy-2-ethyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

(a) In a similar manner as in example 1(a), 3-(benzyloxy)-2-ethyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (1.10 g) was prepared from 3-(benzyloxy)-2-ethyl-4H-pyran-4-one (1.20 g, 5.2 mmol) and 2,2,2-trifluoroethylamine hydrochloride (3.57 g, 26.1 mmol) in pyridine (10 mL). Yield=67%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 7.07-7.59 (m, 6H), 6.51 (d, J=7.7 Hz, 1H), 5.20 (s, 2H), 4.38 (q, J=7.7 Hz, 2H), 2.58 (q, J=7.5 Hz, 2H) and 0.97 (t, J=7.5 Hz, 3H); MS m/z 312 [M+1]⁺. (b) In a similar manner as described in example 1(b), 2-ethyl-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.30 g) was prepared from 3-(benzyloxy)-2-ethyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.90 g, 2.9 mmol) with 10% palladium on charcoal (wet, 90 mg) in methanol (5 mL) and ethanol (35 mL) under hydrogen at 15 psi for 1.5 hours. Yield=47%; ¹H NMR (DMSO-D₆, 400 MHz) δ (ppm): 7.58 (d, J=7.3 Hz, 1H), 6.41 (d, J=7.3 Hz, 1H), 4.92 (q, J=8.1, 2H), 2.72 (t, J=7.5 Hz, 2H) and 1.20 (t, J=7.5 Hz, 3H); MS m/z 222 [M+1]⁺.

Example 3 Preparation of 1-(2,2-difluoroethyl)-3-hydroxy-2-methyl pyridin-4(1H)-one

(a) Preparation of 3-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one

3-(Benzyloxy)-2-methyl-4H-pyran-4-one (432 mg, 2.0 mmol) was mixed with 2,2-difluoroethylamine (655 mg, 8.0 mmol) and triethylamine hydrochloride (1.10 g, 8.0 mmol) in pyridine (6 mL) in a sealed vial. The reaction mixture was heated at 110° C. for overnight. The solid was filtered and washed with ethyl acetate. The filtrate was concentrated under reduced pressure and the residue was mixed with water, and then extracted with ethyl acetate. The organic layer was washed with water and brine. The product was purified by column chromatography on silica gel with 5% methanol in ethyl acetate as eluant to give 3-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one (337 mg) as pale-yellow solid. Yield=60%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 7.66 (d, J=7.1 Hz, 1H), 7.16-7.55 (m, 5H), 6.46 (d, J=7.1 Hz, 1H), 5.55 (t, J=55.0 Hz, 1H), 4.45 (t, J=14.8 Hz, 1H) and 2.20 (s, 3H); MS m/z 280 [M+1]⁺.

(b) In a similar manner as example 1(b), 1-(2,2-difluoroethyl)-3-hydroxy-2-methylpyridin-4(1H)-one (160 mg) was prepared from 3-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one (337 mg, 1.2 mmol) with 10% Pd/C (wet, 90 mg) in methanol under 1 atmosphere of hydrogen using a balloon for 5 minutes. Yield=70%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 7.60 (d, J=7.3 Hz, 1H), 6.39 (d, J=7.3 Hz, 1H), 6.23 (tt, J=54.0, 2.9 Hz, 1H), 4.51 (td, J=14.8, 2.9 Hz, 2H) and 2.43 (s, 3H); MS m/z 190 [M+1]⁺.

Example 4 Preparation of 5-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

(a) Preparation of 5-(benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

5-(Benzyloxy)-2-methyl-4H-pyran-4-one (4.32 g, 20.0 mmol) was mixed with trifluoroethylamine (6.92 g, 70.0 mmol) in 6N HCl (11.7 mL) and ethanol (5.8 mL). The reaction mixture was heated in a sealed flask at 100° C. for 20 hours. The mixture was then concentrated in vacuo and the residue was diluted with water. The solid was filtered, washed with water and ether to give 5-(benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (5.01 g) as white solid. Yield=84%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 7.99 (s, 1H), 7.14-7.65 (m, 5H), 6.80 (s, 1H), 4.91-5.25 (m, 4H), 2.53 (s, 3H).

(b) 5-(Benzyloxy)-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (45.8 g, 164 mmol) was mixed with 6N HCl (100 mL) and isopropanol (20 mL). The mixture was heated at 110° C. oil bath for 8 hours and then concentrated by rotary evaporator. The residue was triturated with acetone and ether to give 5-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one hydrochloride (24.5 g). Yield=65%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 8.18 (s, 1H), 7.21 (s, 1H), 5.31 (q, J=8.2 Hz, 2H) and 2.67 (s, 3H).

Example 5 Preparation of 1-(2,2-difluoroethyl)-5-hydroxy-2-methyl pyridin-4(1H)-one

(a) In a similar manner as described in example 4(a), 5-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one (2.20 g) was prepared from a mixture of 5-(benzyloxy)-2-methyl-4H-pyran-4-one (3.00 g, 13.8 mmol), difluoroethylamine (2.48 g, 55.2 mmol), triethylamine hydrochloride (5.58 g, 55.2 mmol) and pyridine (15 mL). Yield=58%; ¹H NMR (90 MHz, MeOD-D₄) δ (ppm): 7.53 (s, 1H), 7.27-7.45 (m, 5H), 6.36 (s, 1H), 5.56-6.77 (tt, J=54.9, 3.6 Hz, 1H), 5.04 (s, 2H), 4.24-4.60 (td, J=14.9, 2.7, 2H) and 2.36 (s, 3H); MS m/z 280 [M+1]⁺. (b) In a similar manner as described in example 1(b), 1-(2,2-difluoroethyl)-5-hydroxy-2-methylpyridin-4(1H)-one (230 mg) was prepared from 5-(benzyloxy)-1-(2,2-difluoroethyl)-2-methylpyridin-4(1H)-one (500 mg, 1.80 mmol) with 10% Pd/C (wet, 50 mg) in methanol (40 mL) under hydrogen at 15 psi pressure in a Parr apparatus for 27 minutes. Yield=99%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 7.46 (s, 1H), 6.37 (s, 1H), 5.62-6.83 (tt, J=54.9, 3.6 Hz, 1H), 4.26-4.60 (td, J=15.3, 2.4 Hz, 2H) and 2.38 (s, 3H); MS m/z 190 [M+1]⁺.

Example 6 Preparation of 3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

(a) 5-(Benzyloxy)-4-oxo-4H-pyran-2-carboxylic acid (10.5 g, 42.7 mmol) was dissolved in sodium hydroxide solution (1.71 g, 42.7 mmol in 77 mL de-ionized water). 2,2,2-Trifluoroethylamine hydrochloride (23.1 g, 171 mmol) was added and the resulting suspension was stirred at 70° C. (oil-bath temperature) in the sealed flask for 17 hours. The reaction mixture was then filtered and the off-white solid was washed with de-ionized water (20 mL×5) to give 5-(benzyloxy)-4-oxo-1-(2,2,2-trifluoroethyl)-1,4-dihydropyridine-2-carboxylic acid (6.00 g). Yield=43%; ¹H NMR (MeOD-D₄, 90 MHz) δ 7.30 (s, 1H), 6.76-7.09 (m, 5H), 6.71 (s, 1H), 4.93 (d, J=8.4 Hz, 2H) and 4.65 (s, 2H); MS m/z 328 [M+1]⁺. (b) 5-(Benzyloxy)-4-oxo-1-(2,2,2-trifluoroethyl)-1,4-dihydropyridine-2-carboxylic acid (4.70 g, 14.4 mmol) was mixed with DMF (25 mL) and heated to 130° C. (bath temperature) for 3 hours. The mixture was concentrated under reduced pressure using a rotary evaporator and the residue was mixed with ethyl acetate (50 mL). It was then stirred for 2 hours at room temperature and filtered. The filtrate was concentrated to give 3-(benzyloxy)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (3.58 g). Yield=69%; ¹H NMR (DMSO-D₆, 400 MHz) δ (ppm) 7.57-7.84 (m, 2H), 7.22-7.57 (m, 5H), 6.25 (br. s, 1H) and 4.69-5.28 (m, 4H); MS m/z 284 [M+1]⁺. (c) 3-(Benzyloxy)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (1.2 g, 4.2 mmol) was mixed with 10% Palladium on charcoal (wet, 0.12 g) in ethanol (70 mL). The resulting mixture was hydrogenated at 15 psi of hydrogen pressure for 1.5 hours. Palladium was removed by filtration through a layer of Celite™ and the Celite™ cake was washed with methanol (5 mL×3). The filtrate was evaporated to give 3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.78 g) as white solid. Yield=95%; ¹H NMR (DMSO-D₆, 400 MHz) δ (ppm) 7.60 (d, J=7.1 Hz, 1H), 7.46 (s, 1H), 6.23 (d, J=7.1 Hz, 1H) and 4.80-5.00 (m, 2H); MS m/z 194 [M+1]⁺.

Example 7 Preparation of 3-hydroxy-2-(hydroxymethyl)-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

5-Hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one hydrochloride (4.87 g. 20.0 mmol) was mixed with 37% formaldehyde (30 mL) and 6N sodium hydroxide (7 mL, 42.0 mmol). The reaction mixture was stirred at 39-42° C. for 11 hours, and then additional 37% formaldehyde (30 mL) was added. The reaction mixture was stirred at 37° C. for 12 hours and then left at room temperature for a further 12 hours. The solid was filtered and the filtrate was acidified to pH about 5 to 6. The solution was concentrated with silica gel and the product was purified by column chromatography with a gradient mixture of 5-10% methanol in ethyl acetate as eluant to give the title compound 3-hydroxy-2-(hydroxymethyl)-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (3.02 g) as pale-peach solid. Yield 63.5%; ¹H NMR (DMSO-D₆+D₂O, 90 MHz) δ (ppm): 6.20 (s, 1H), 5.15 (q, J=8.8 Hz, 2H), 4.33-4.92 (m, 2H) and 2.37 (s, 3H); MS m/z 238 [M+1]⁺.

Example 8 A. Preparation of 2-[(dimethylamino)methyl]-3-hydroxy-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

5-Hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one hydrochloride (415 mg, 1.7 mmol) was mixed with N,N,N′,N′-tetramethylmethanediamine (4 mL) in ethanol (10 mL) and heated at 80° C. for 21 hours. The reaction mixture was concentrated by rotary evaporator and the residue was triturated with water to give 2-[(dimethylamino)methyl]-3-hydroxy-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (315 mg) as white solid. Yield=70%; ¹H NMR (DMSO-D₆+D₂O, 90 MHz) δ (ppm): 6.20 (s, 1H), 5.15 (q, J=8.8 Hz, 2H), 4.69 (br. s, 2H) and 2.37 (s, 3H); MS m/z 265 [M+1]⁺.

B. Preparation of 2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

In a similar manner, 2-[(dimethylamino)methyl]-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.21 g) was prepared from 3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.60 g, 3.1 mmol) reacted with N,N,N′,N′-tetramethyldiaminomethane (8.50 mL, 62.2 mmol) in ethanol (10 mL) at 75° C. for 20 hours. Yield=27%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 7.81 (d, J=7.5 Hz, 1H), 6.52 (d, J=7.5 Hz, 1H), 5.07 (d, J=8.0 Hz, 2H), 4.60 (s, 2H) and 2.94 (s, 6H); MS m/z 251 [M+1]⁺.

C. Preparation of 1-(2,2-difluoroethyl)-2-[(dimethylamino)methyl]-3-hydroxy-6-methyl pyridin-4(1H)-one

In a similar manner, 1-(2,2-difluoroethyl)-2-[(dimethylamino)methyl]-3-hydroxy-6-methylpyridin-4(1H)-one (0.41 g) was prepared from 1-(2,2-difluoroethyl)-5-hydroxy-2-methylpyridin-4(1H)-one (0.40 g, 2.1 mmol) and N,N,N′,N′-tetramethyldiaminomethane (4.3 mL, 31.7 mmol) in ethanol (10 mL) at 75° C. for 19 h. Yield=78%; ¹H NMR (DMSO-D₆, 90 MHz) δ ppm: 6.45 (tt, J=55.1, 3.5 Hz, 1H), 6.24 (s, 1H), 4.74 (td, J=14.6, 3.5 Hz, 2H), 3.55 (s, 2H), 2.37 (s, 3H), 2.17 (s, 6H); MS m/z 247 [M+1]⁺.

Example 9 Preparation of 3-hydroxy-6-methyl-2-(piperidin-1-yl methyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

3-Hydroxy-2-(hydroxymethyl)-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (375 mg, 1.6 mmol) was mixed with acetonitrile at 80° C. and the thionyl chloride (753 mg, 6.3 mmol) was added. The reaction mixture was stirred for 5 minutes and then concentrated by rotary evaporator to give 2-(chloromethyl)-3-hydroxy-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one hydrochloride. The chloride compound was added to a solution of piperidine (672 mg, 7.9 mmol) in isopropanol (5 mL) at room temperature. Five minutes later, the reaction mixture was diluted with water and extracted with ethyl acetate. The organic layer was washed with water twice and brine, dried and concentrated. The residue was triturated with ether/hexanes to give 3-hydroxy-6-methyl-2-(piperidin-1-ylmethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (165 mg) as pale orange solid. Yield=34%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 6.37 (s, 1H), 3.72 (br. s, 2H), 2.45 (br. m, 7H) and 1.51 (br. m, 6H); MS m/z 305 [M+1]⁺.

Example 10 Preparation of N-methyl-N2-[2,2,2-trifluoro-1-(3-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)ethyl]-D-alaninamide and N-methyl-N2-[2,2,2-trifluoro-1-(3-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)ethyl]-L-alaninamide (Apo6998 and Apo6999)

To a solution of 3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride (100.0 g, 0.62 mol) dissolved in a solution of 6N NaOH (206.9 mL) at ice-water bath was added trifluoroacetaldehyde methyl hemiacetal (131.9 mL, 1.24 mmol). The resulting solution was heated to 95° C. for overnight. The reaction mixture was then cooled, and at ice-water bath the pH of the mixture was adjusted to about 5 using a 6N HCl solution. The precipitated solid was collected by filtration, and the solid was thoroughly washed with de-ionized water (100 mL×2), and then dried under vacuum at 43° C. for overnight to afford 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (94.8 g) as a white solid. Yield=68% yield; ¹H NMR (90 MHz, MeOD-D₄) δ (ppm): 7.60 (d, J=7.1 Hz, 1H), 6.40 (d, J=7.2 Hz, 1H), 5.92 (q, J=8.2 Hz, 1H), 3.98 (s, 3H); MS m/z 224 [M+1]⁺, 158 (100%).

To an ice cooled suspension of 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.60 g, 7.2 mmol) in 50 mL of acetonitrile was added dropwise SOCl₂ (0.80 mL, 10.8 mmol) followed by pyridine (0.6 mL, 7.2 mmol). The resulting suspension was stirred for 0.5 h and then refluxed for 2 h. The reaction mixture was evaporated to dryness. To a suspension of the residue in 10 mL of acetonitrile was added a suspension of L-H-Ala-NHMe.HCl (1.19 g, 8.6 mmol) and Et₃N (4.0 mL, 28.7 mmol) in 20 mL of acetonitrile. The resulting mixture was stirred at RT for overnight. The reaction mixture was evaporated to dryness, and the residue was purified by flash chromatography on silica gel (10% conc NH₄OH in IPA as eluant) to afford 2.20 g of the two diastereoisomers, Apo6998 and Apo6999. A sample of each diastereoisomers was obtained through further purification by Biotage using reverse phase C18 cartridge.

More polar isomer by HPLC (Rt=3.43 min) (110 mg). ¹H NMR (400 MHz, MeOD-D₄) δ (ppm): 7.68 (d, J=7.1 Hz, 1H), 6.41 (d, J=7.1 Hz, 1H), 4.68-4.80 (m, 1H), 3.83 (s, 3H), 3.41-3.56 (m, 1H), 2.57 (s, 3H), 1.30 (d, J=6.1 Hz, 3H); MS m/z 330 [M+Na]⁺, 308 [M+1]⁺, 126 (100%).

Less polar isomer by HPLC (Rt=3.68 min) (100 mg). ¹H NMR (400 MHz, MeOD-D₄) δ (ppm): 7.70 (d, J=7.1 Hz, 1H), 6.44 (d, J=7.1 Hz, 1H), 4.60-4.70 (m, 1H), 3.79 (s., 3H), 3.20-3.24 (m, 1H), 2.75 (s, 3H), 1.28 (d, J=6.1 Hz, 3H); MS m/z 330 [M+Na]⁺, 308 [M+1]⁺, 126 (100%).

HPLC condition: Column: Symmetry C18, 5 μm; 3.9 mm×150 mm; Flow rate: 1.0 mL/min; Mobile phase: A=0.035% HClO₄, B=Acetonitrile; Gradient (min-B %): 0-10, 10-100, 12-100, 14-50.

Example 11 Preparation of 2-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methylpyridin-4(1H)-one (Apo7041)

To a suspension of 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (5.00 g, 22.4 mmol) in 40 mL of acetonitrile at ice-water bath was added Vilsmeier's reagent (4.30 g, 33.6 mmol) portionwise. The resulting mixture was stirred for 2 h before being added to a suspension of dimethylamine hydrochloride (6.00 g, 73.6 mmol) and Et₃N (15.0 mL, 107.6 mmol) in 30 mL of acetonitrile. The resulting suspension was stirred at RT for overnight. The solid was filtered off and the filtrate was concentrated to dryness. The residue was purified by flash chromatography on silica gel (10% MeOH in EtOAc as eluant) to afford title compound, Apo7041 (1.8 g). Yield=32%; ¹H NMR (90 MHz, CD₃OD-D₄) δ (ppm): 7.63 (d, J=7.3 Hz, 1H), 6.41 (d, J=7.3 Hz, 1H), 4.78 (q, J=8.1 Hz, 1H), 3.99 (s, 3H), 2.41 (s, 6H); MS m/z 273 [M+Na]⁺, 251 [M+1]⁺, 206 (100%).

Example 12 A. Preparation of 3-hydroxy-1-methyl-2-{2,2,2-trifluoro-1-[methyl(prop-2-yn-1-yl)amino]ethyl}pyridin-4(1H)-one (Apo7057)

To 20 mL acetonitrile cooled in an ice-water bath was added DMF (0.42 mL, 5.4 mmol) followed by oxalyl chloride (0.47 mL, 5.4 mmol) dropwise. To this resulting suspension was added 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.0 g, 4.5 mmol) in one portion. The mixture was then stirred for 2 h. Then, Et₃N (2.50 mL, 17.9 mmol) was added to this reaction mixture followed by N-methyl propargylamine (0.75 mL, 9.0 mmol). The reaction mixture was stirred at RT for overnight. The solid was filtered off, and the filtrate was concentrated to dryness. The residue was purified by flash chromatography on silica gel (5% MeOH in CH₂Cl₂ as eluant) to afford the title compound, Apo7057 (570 mg) as an orange powder. Yield=46.4%; ¹H NMR (400 MHz, DMSO+a few drops of D₂O) δ (ppm): 7.6 (br. s., 1H), 6.25 (d, J=7.1 Hz, 1H), 5.15 (br. s., 1H), 3.87 (s, 3H), 3.37-3.67 (m, 2H), 3.23 (br. s., 1H), 2.32 (br. s., 3H); MS m/z 275 [M+1]⁺, 206 (100%).

B. Preparation of 3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-one (Apo7058)

In a similar manner, Apo7058 was prepared from 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.0 g, 4.5 mmol) and piperidine (0.88 mL, 8.9 mmol). The title compound Apo7058 (700 mg) was obtained as a white solid after purification by flash chromatography (4% MeOH in CH₂Cl₂ as eluant). Yield=54%; ¹H NMR (400 MHz, DMSO-D6, 75° C.) δ (ppm): 7.59 (d, J=6.8 Hz, 1H), 6.19 (d, J=6.8 Hz, 1H), 4.82 (q, J=9.0 Hz, 1H), 3.88 (s, 3H), 2.46-2.84 (m, 4H), 1.29-1.74 (m, 6H) MS m/z 291 [M+1]+, 206 (100%).

C. Preparation of 3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(4-methylpiperazin-1-yl)ethyl]pyridin-4(1H)-one (Apo7073)

In a similar manner, Apo7073 was prepared from 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.0 g, 4.5 mmol) and 1-methylpiperazine (1.0 mL, 9.0 mmol). The title compound Apo7073 (401 mg) was obtained after purification by Biotage reverse C18 column. Yield=29%; ¹H NMR (400 MHz, DMSO-d6, 75° C.) δ (ppm): 7.63 (d, J=6.8 Hz, 1H), 6.21 (d, J=7.4 Hz, 1H), 4.94 (q, J=8.5 Hz, 1H), 3.86 (s, 3H), 3.05 (br. s., 4H), 2.92 (br. s., 4H), 2.64 (s, 3H); MS m/z 306 [M+1]⁺, 206 (100%).

D. Preparation of 2-[1-(cyclopropylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1-methyl pyridin-4(1H)-one (Apo7074)

In a similar manner, Apo7074 was prepared from 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.0 g, 4.5 mmol) and cyclopropylamine (0.62 mL, 9.0 mmol). The title compound Apo7074 (470 mg) was obtained after purification by flash chromatography (5% MeOH in CH₂Cl₂ as eluant). Yield=40%; ¹H NMR (400 MHz, DMSO+a few drops of D₂O) δ (ppm): 7.67 (d, J=6.8 Hz, 1H), 6.25 (d, J=7.1 Hz, 1H), 4.70 (q, J=8.1 Hz, 1H), 3.74 (s, 3H), 2.04 (br. s., 1H), 0.34-0.43 (m, 4H); MS m/z 263 [M+1]⁺, 206 (100%).

E. Preparation of 3-hydroxy-1-methyl-2-[2,2,2-trifluoro-1-(prop-2-en-1-ylamino)ethyl]pyridin-4(1H)-one (Apo7075)

In a similar manner, Apo7075 was prepared from 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.0 g, 4.5 mmol) and allylamine (0.67 mL, 9.0 mmol). The title compound Apo7075 (497 mg) was obtained after purification by flash chromatography (5% MeOH in CH₂Cl₂ as eluant). Yield=42%; ¹H NMR (400 MHz, DMSO+a few drops of D₂O) δ (ppm): 7.65 (d, J=7.1 Hz, 1H), 6.24 (d, J=7.4 Hz, 1H), 5.70-5.80 (m, 1H), 5.14 (d, J=17.4 Hz, 1H), 5.06 (d, J=10.1 Hz, 1H), 4.63 (q, J=8.2 Hz, 1H), 3.67 (s, 3H), 3.15-3.19 (m, 2H); MS m/z 263 [M+1]⁺, 206 (100%).

Example 13 A. Preparation of 5-(benzyloxy)-3-chloro-2-methyl pyridin-4(1H)-one

To a solution of 5-(benzyloxy)-2-methylpyridin-4(1H)-one (9.00 g, 41.8 mmol) in 2M sodium hydroxide (62.5 mL, 125 mmol) under ice-water bath, a solution of 10-14% sodium hypochlorite (62.5 mL) was added slowly during 20 minutes. The reaction mixture was stirred at room temperature for another hour. The reaction mixture was carefully neutralized with 6N HCl to pH about 7 with external cooling to keep the internal temperature below 25° C. The solid was filtered and washed with water (3×), then dried in a vacuum oven for overnight. Thus, 5-(benzyloxy)-3-chloro-2-methylpyridin-4(1H)-one (9.03 g) was obtained as a white solid. Yield=86%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 11.74 (br. s, 1H), 7.14-7.68 (m, 6H), 5.02 (s, 2H) and 2.33 (s, 3H).

B. Preparation of 5-(benzyloxy)-3-chloro-2-(hydroxymethyl)pyridin-4(1H)-one

In a similar manner, 5-(benzyloxy)-3-chloro-2-(hydroxymethyl)pyridin-4(1H)-one (10.50 g) was prepared from 5-(benzyloxy)-2-(hydroxymethyl)pyridin-4(1H)-one (11.56 g, 50 mmol) and a solution of 10-14% sodium hypochlorite (75 mL) in 2M sodium hydroxide (75 mL) solution. Yield=81%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 11.35 (br. s, 1H), 7.05-7.66 (m, 6H), 5.79-6.32 (m, 1H), 5.03 (s, 2H) and 4.54 (s, 2H).

C. Preparation of 5-(benzyloxy)-3-chloro-1,2-dimethylpyridin-4(1H)-one

5-(Benzyloxy)-3-chloro-2-methylpyridin-4(1H)-one (3.00 g, 12.0 mmol) was suspended in 25 mL of DMF. Potassium carbonate (3.30 g, 24.0 mmol) was added followed by the addition of iodomethane (1.53 mL, 24.0 mmol). The progress of the reaction was monitored by TLC (30% ethyl acetate in hexanes). Upon completion, the reaction was allowed to stir at room temperature. Water was added and a white precipitate formed. The solid was collected by suction filtration, allowed to air dry and then further dried under vacuum. Thus, 5-(benzyloxy)-3-chloro-1,2-dimethylpyridin-4(1H)-one (2.00 g) was obtained. Yield=63%; ¹H NMR (MeOD-D₄, 90 MHz,) δ (ppm): 7.61 (s, 1H), 7.27-7.46 (m, 5H), 5.21 (s, 2H), 3.75 (s, 3H) and 2.54 (s, 3H).

D. Preparation of 5-(benzyloxy)-3-chloro-2-(hydroxymethyl)-1-methylpyridin-4(1H)-one

In a similar manner, 5-(benzyloxy)-3-chloro-2-(hydroxymethyl)-1-methylpyridin-4(1H)-one (7.52 g) was prepared from 5-(benzyloxy)-3-chloro-2-(hydroxymethyl)pyridin-4(1H)-one (10.0 g, 37.6 mmol), iodomethane (10.7 g, 75.2 mmol) and potassium carbonate (10.3 g, 75.2 mmol) in DMF (50 mL). Yield=72%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 7.77 (s, 1H), 7.17-7.58 (m, 5H), 5.65 (br. s, 1H), 5.04 (s, 2H), 4.70 (br. s, 2H) and 3.81 (s, 3H).

E. Preparation of 5-(benzyloxy)-3-chloro-1-methyl-4-oxo-1,4-dihydropyridine-2-carboxylic acid

To a mixture of 5-(benzyloxy)-3-chloro-2-(hydroxymethyl)-1-methylpyridin-4(1H)-one (4.90 g, 17.5 mmol), TEMPO (120 mg, 0.77 mmol) and potassium bromide (120 mg, 1.00 mmol) in acetone (50 mL) and saturated sodium bicarbonate (40 mL) below 7° C. was added dropwise a 10-14% sodium hypochlorite (50 mL) solution during 30 minutes. After being stirred for 2 hours, the reaction mixture was diluted with water and adjusted to pH about 1.5 with 6N HCl. The solid was filtered and washed with water to give 5-(benzyloxy)-3-chloro-1-methyl-4-oxo-1,4-dihydropyridine-2-carboxylic acid (2.89 g) as a white solid. Yield=56%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 7.79 (s, 1H), 7.16-7.62 (m, 5H), 5.03 (s, 2H) and 3.67 (s, 3H); MS m/z 294 [M+1]⁺.

F. Preparation of 3-(benzyloxy)-5-chloro-1-methylpyridin-4(1H)-one

5-(Benzyloxy)-3-chloro-1-methyl-4-oxo-1,4-dihydropyridine-2-carboxylic acid (3.50 g, 11.9 mmol) was heated in DMF (10 mL) for one hour. The reaction mixture was concentrated by rotary evaporation and the residue was triturated with ethyl acetate/ether to give 3-(benzyloxy)-5-chloro-1-methylpyridin-4(1H)-one (2.80 g) as a pale brown solid. Yield=94%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 8.08 (d, J=1.8 Hz, 1H), 7.68 (d, J=1.8 Hz, 1H), 7.19-7.58 (m, 5H), 5.01 (s, 2H) and 3.67 (s, 3H).

Example 14 A. Preparation of 3-chloro-5-hydroxy-1-methylpyridin-4(1H)-one

3-(Benzyloxy)-5-chloro-1-methylpyridin-4(1H)-one (2.70 g, 10.8 mmol) was mixed in 6N HCl (15 mL) and ethanol (10 mL). After being refluxed for 2 hours, the reaction mixture was concentrated by rotary evaporator. The residue was mixed with water (5 mL) and basified to pH 8-9 with concentrated ammonia. An off-white precipitate came out, ant the mixture was again concentrated in vacuo to remove volatiles. The off-white solid was collected by suction filtration and dried to give 3-chloro-5-hydroxy-1-methylpyridin-4(1H)-one (1.32 g). Yield=76.6%; ¹H NMR (DMSO-D₆, 90 MHz) δ (ppm): 7.98 (s, 1H), 7.47 (s, 1H) and 3.67 (s, 3H).

B. Preparation of 3-chloro-5-hydroxy-1,2-dimethylpyridin-4(1H)-one

In a similar manner, 3-chloro-5-hydroxy-1,2-dimethylpyridin-4(1H)-one (600 mg), was prepared by refluxing a mixture of 5-(benzyloxy)-3-chloro-1,2-dimethylpyridin-4(1H)-one (2.00 g, 7.6 mmol) with 6N HCl (20 mL) and methanol (10 mL) at 100° C. for 2 hours. Yield=46%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 8.08 (s, 1H) 4.08 (s, 3H) and 2.72 (s, 3H); MS m/z 174 [M+1]⁺.

Example 15 A. Preparation of 3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one

3-Chloro-5-hydroxy-1,2-dimethylpyridin-4(1H)-one (500 mg, 2.80 mmol) was suspended in trifluoroacetaldehyde methyl hemiacetal (3 mL). Potassium carbonate (119 mg, 0.86 mmol) was added and the mixture was heated to 120° C. After 2.5 hours, the reaction mixture was allowed to cool to room temperature, then diluted with methanol and filtered. The filtrate was concentrated to dryness and diluted with acetone. The solution was filtered and the filtrate was concentrated to give 3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (650 mg) as a pink solid. Yield=85%; ¹H-NMR (MeOD-D₄, 90 MHz) δ (ppm): 5.9 (q, J=9.1 Hz, 1H), 4.01 (s, 3H) and 2.65 (s, 3H); MS-ESI m/z 272 [M+1]⁺.

B. Preparation of 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one

In a similar manner, 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.40 g) was prepared from 3-chloro-5-hydroxy-1-methylpyridin-4(1H)-one (1.27 g, 8.0 mmol) and trifluoroacetaldehyde methyl hemiacetal (12.7 mL) in presence of potassium carbonate (0.22 g, 1.6 mmol). Yield=68%; ¹H NMR (DMSO-D₆) δ (ppm): 8.10 (s, 1H), 5.80 (q, J=8.7 Hz, 1H) and 3.88 (s, 3H); MS m/z 258 [M+1]⁺.

Example 16 A. Preparation of 3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

3-Chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (300 mg, 1.10 mmol) was suspended in 10 mL of acetonitrile and thionyl chloride (398 μL, 5.50 mmol) was added dropwise. The reaction was stirred at room temperature. After 2 hours, the reaction was concentrated. The crude was diluted with 10 mL of methanol and sodium borohydride (329 mg, 8.80 mmol) was added in small portions. After 15 hours, the reaction was filtered and the filtrate was concentrated in vacuo. The resulting solid was dissolved in methanol and ethyl acetate added, filtered and concentrated. The crude product was purified by column chromatography on silica gel using a mixture of 30% EtOAc in MeOH as eluant. Fractions rich in product were combined and evaporated to dryness. The residue product was recrystallised from methanol/ethyl acetate to give 3-chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (172 mg) as a white solid. Yield=61%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 4.1 (q, J=9.0 Hz, 2H), 3.99 (s, 3H) and 2.77 (s, 3H); MS m/z 256 [M+1]⁺.

B. Preparation of 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

In a similar manner, 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (117 mg) was prepared from 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (580 mg, 2.30 mmol). Yield=22%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 8.04 (s, 1H), 3.91 (q, J=9.9 Hz, 2H) and 3.84 (s, 3H); MS m/z 242 [M+1]⁺.

Example 17 A. Preparation of 3-chloro-6-[1-(dimethylamino)-2,2,2-trifluoroethyl]-5-hydroxy-1,2-dimethylpyridin-4(1H)-one

3-Chloro-5-hydroxy-1,2-dimethyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (618 mg, 2.3 mmol) was mixed with pyridine (276 μL, 3.4 mmol) in acetonitrile (10 mL) at room temperature. Thionyl chloride (249 μL, 3.41 mmol) was added dropwise. After being stirred at room temperature for 30 minutes, the reaction mixture was concentrated by rotary evaporation. The residue was dried under vacuum and then mixed with ethanol (20 mL) under ice-water bath. An ethanolic dimethylamine (5.6 M, 4.06 mL, 22.8 mmol) solution was added at about 5° C. and the mixture was stirred for 20 minutes. The reaction mixture was concentrated by rotary evaporation. The residue was mixed with water (10 mL) and the pH of the solution was adjusted to 5.5. The precipitated solid was collected by suction filtration, and washed with water, then triturated with ether/hexanes to give 3-chloro-6-[1-(dimethylamino)-2,2,2-trifluoroethyl]-5-hydroxy-1,2-dimethylpyridin-4(1H)-one (380 mg) as an off-white solid. Yield=56%; ¹H NMR (CDCl₃, 90 MHz) δ (ppm): 4.88 (q, J=8.6 Hz, 1H), 4.08 (s, 3H), 2.65-2.81 (m, 3H) and 2.39 (s, 6H); MS m/z 299 [M+1]⁺.

B. Preparation of 5-chloro-2-(1-(di methylamino)-2,2,2-trifluoroethyl)-3-hydroxy-1-methyl pyridin-4(1H)-one

In a similar manner, 5-chloro-2-(1-(dimethylamino)-2,2,2-trifluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (290 mg) was prepared from 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (386 mg, 1.5 mmol). Yield=68%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 8.04 (s, 1H), 4.69-4.85 (m, 1H), 4.05 (br. s, 3H) and 2.42 (br. s, 6H); MS m/z 285 [M+1]⁺.

C. Preparation of 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-(piperidin-1-yl)ethyl)pyridin-4(1H)-one

In a similar manner, 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-(piperidin-1-yl)ethyl)pyridin-4(1H)-one (302 mg) was prepared from 5-chloro-3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (386 mg, 1.5 mmol). Yield=60%; ¹H NMR (MeOD-D₄, 90 MHz) δ (ppm): 8.03 (br. s, 1H), 4.57-4.83 (m, 1H), 3.74-4.35 (m, 3H), 2.21-3.02 (m, 4H) and 1.44-1.89 (m, 6H); MS m/z 325 [M+1]⁺.

Example 18 A. Preparation of 2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methyl pyridin-4(1H)-one (Apo7078)

A sealed suspension of 3-hydroxy-1-methypyridin-4(1H)-one (1.00 g, 8.0 mmol) and potassium carbonate (0.11 g, 0.8 mmol) in 2.4 mL of difluroacetaldehyde ethyl hemiacetal was heated to 50° C. for 18 h. The volatile components were evaporated under reduced pressure. The residue was dissolved in 3 mL of de-ionized water then cooled in an ice-water bath, and the pH was adjusted to 5-6 with a 1N HCl solution. The precipitate was collected by suction filtration and dried. Thus, the title compound Apo7078 was obtained (410 mg) as a white solid. Yield=25%; ¹H NMR (400 MHz, CD₃OD) δ (ppm): 7.62 (d, J=7.1 Hz, 1H), 6.41 (d, J=7.1 Hz, 1H), 6.30 (dt, ³J=55.8 Hz, ²J=5.1 Hz, 1H), 5.45 (dt, ²J=5.1 Hz, ³J=11.4 Hz, 1H), 3.96 (s, 3H); MS m/z 206 [M+1]⁺, 188 (100%).

B. Preparation of 2-(2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (Apo7080)

To 10 mL of acetonitrile at ice-water bath was added DMF (0.14 mL, 1.8 mmol) followed by oxalyl chloride (0.15 mL, 1.8 mmol) dropwise. To this resulting suspension was added 2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (0.30 g, 1.5 mmol) in one portion, and the resulting mixture was stirred for 2 h. A solid was collected by filtration, and it was dissolved in 150 mL of acetonitrile. To this resulting solution was added Pd/C (10%, wet, 0.20 g, 66.7% w/w), and the mixture was subjected to hydrogenation under 40 psi hydrogen pressure for 2 h. The catalyst was filtered off, and the filtrate was evaporated to dryness. The residue was dissolved in de-ionized water, and the pH was adjusted to 5-6 using a 6N NaOH solution. The precipitate was collected via suction filtration to afford the crude product (100 mg) as an off-white solid. The crude was further purified by Biotage using reversed phase C18 cartridge to afford the title compound, Apo7080 (66 mg) as white solid. Yield=24%; ¹H NMR (400 MHz, CD₃OD) δ (ppm): 7.65 (d, J=7.2 Hz, 1H), 6.41 (d, J=7.2 Hz, 1H), 6.19 (tt, J=56.5, 4.7 Hz, 1H), 3.83 (s, 3H), 3.51 (dt, ³J=15.9 Hz, ²J=4.6 Hz, 2H); MS m/z 190 [M+1]⁺, 188 (100%).

Example 19 Preparation of N-2-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl] methyl}-N-methyl-L-alaninamide (Apo7033)

A mixture of 5-(benzyloxy)-2-(chloromethyl)-1-methylpyridin-4(1H)-one hydrochloride (7.55 g, 25.0 mmol), H-Ala-NHMe.HCl (5.14 g, 37.0 mmol) and diisopropylethylamine (12.5 mL, 72.0 mmol) in CH₃CN (50 mL) was heated at 85° C. under a nitrogen atmosphere for overnight. Volatiles were removed in vacuo, and the residue was pre-purified by column chromatography on silica gel using a mixture of MeOH and ethyl acetate as eluant (solvent gradient of 10, 15 and 20% MeOH in ethyl acetate). The fractions rich in product were combined and evaporated to dryness. Further purification by column chromatography on silica gel using a mixture of H₂O and CH₃CN (1-5% H₂O content) and then a 10% MeOH in dichloromethane solution afforded (S)-2-((5-(benzyloxy)-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)methylamino)-N-methylpropanamide (7.17 g) in 87% yield. MS m/z 352 [M+Na]⁺, 330 (100%) [M+1]⁺, 228, 138, 91.

A mixture of (S)-2-((5-(benzyloxy)-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)methylamino)-N-methylpropanamide (7.04 g, 21.4 mmol) and 10% Pd/C (0.90 g) in MeOH (70 mL) was subjected to hydrogenation in a Parr apparatus at 50 psi of hydrogen pressure for 2 h. The reaction mixture was filtered over celite and the filtrate was concentrated in vacuo. The resulting solid was dried in a vacuum oven at 44° C. for overnight. Thus, (S)-2-((5-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)methylamino)-N-methylpropanamide was obtained as an orange solid (4.90 g) in 96% yield. ¹H NMR (CD₃COOD) δ (ppm): 7.77 (s, 1H), 7.03 (s, 1H), 4.30-4.34 (m, 3H, OCH₂+CHCH₃), 3.98 (s, 3H), 2.80 (s, 3H), 1.56 (d, J=6.3 Hz, 3H, CHCH₃); MS m/z 262 [M+Na]⁺, 240 (100%) [M+1]⁺, 138, 110.

A mixture of (S)-2-((5-hydroxy-1-methyl-4-oxo-1,4-dihydropyridin-2-yl)methylamino)-N-methylpropanamide (3.13 g, 13.1 mmol), trifluoroacetaldehyde methyl hemiacetal (3.6 mL, 38.0 mmol) and potassium carbonate (2.62 g, 19.0 mmol) in CH₃CN (35 mL) was heated at 75-80° C. for overnight. Analysis of the reaction mixture by TLC using a solvent mixture of 28-30% conc. NH₄OH in IPA as eluant indicated incomplete consumption of the starting material. A further portion of trifluoroacetaldehyde methyl hemiacetal (4 mL) was added, and the mixture was heated at 95-100° C. for another 24 h. On cooling to room temperature, the mixture was purified by column chromatography on silica gel using a mixture of MeOH and ethyl acetate as eluant (solvent gradient of 10, 15 and 20% MeOH in ethyl acetate). Thus, the title compound N-2-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-N-methyl-L-alaninamide, Apo7033, was obtained as a yellowish solid (1.53 g) in 35% yield. ¹H NMR (DMSO-D₆) δ (ppm): 7.79 (t, J=4.4 Hz, 1H, NH), 6.30 (s, 1H), 5.87 (q, J=8.7 Hz, 1H, CHCF₃), 3.82 (s, 3H, NCH₃), 3.61-3.65 (dd, ²J=14.5 and ⁴J=1.9 Hz, 1H, 0.5 NHCH₂), 3.47-3.52 (apparent t, J=15.2 Hz, 1H, 0.5 NHCH₂), 3.08 (q, J=6.8 Hz, 1H, CHCH₃), 2.59 (d, J=4.2 Hz, 3H, NHCH₃), 1.12 (dd, ²J=6.8 and ⁴J=2.3 Hz, 3H, CHCH₃); ¹³C NMR (DMSO-D₆) δ (ppm): 175.0 (C═O), 169.6 (C═O), 149.2, 147.3, 125.6, 125.0 (q, J=283 Hz, CHCF₃), 113.1 (CH), 65.2 (q, J=33 Hz, CHCF₃), 56.9 (CH), 48.9 (CH₂), 36.6 (NCH₃), 25.8 (NHCH₃), 19.6 (CH₃); MS m/z 360 [M+Na]⁺, 338 (100%) [M+1]⁺, 236.

Example 20 N-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-L-alanine (Apo7032)

The experiment in the last step of the previous example (example 19) was repeated (2.9 mmol scale) except that the mixture was purified by column chromatography on silica gel using a mixture of 28-30% conc. NH₄OH and IPA as eluant (solvent gradient of 10, 15 and 20 and 25% NH₄OH in IPA). In this case, the title acid compound N-{[5-hydroxy-1-methyl-4-oxo-6-(2,2,2-trifluoro-1-hydroxyethyl)-1,4-dihydropyridin-2-yl]methyl}-L-alanine (Apo7032) was obtained as an orange solid (0.7 g) in 78% yield. MS m/z 347 [M+Na]⁺, 325 (100%) [M+1]⁺, 236.

Example 21 Preparation of the diastereoisomers of N-methyl-2-[2,2,2-trifluoro-1-(5-hydroxy-6-methyl-4-oxo-1,4-dihydro-pyridin-3-yl)-ethylamino]-propionamide (Apo6884 and Apo6885)

Thionyl chloride (2.5 mL, 33.7 mmol) was added to a suspension of 3-hydroxy-2-methyl-5-(2,2,2-trifluoro-1-hydroxy-ethyl)-1H-pyridin-4-one (1.50 g, 6.7 mmol) in acetonitrile (33 mL) at room temperature. The resulting mixture was stirred for 30 min as a clear solution resulted. The progress of the reaction was monitored by TLC (methanol:dichloromethane, 1:10, v:v), which indicated consumption of the starting material. The reaction mixture was evaporated to dryness to give crude 5-(1-chloro-2,2,2-trifluoro-ethyl)-3-hydroxy-2-methyl-1H-pyridin-4-one as a solid.

The solid was dissolved in acetonitrile (35 mL), and H-Ala-NHMe hydrochloric acid salt (1.15 g, 8.3 mmol) was added followed by triethylamine (4.0 mL, 28.7 mmol). The heterogeneous mixture was stirred for 60 min, while the progress of the reaction was monitored by HPLC Method 1. HPLC analysis of the crude reaction mixture indicated the presence of two product peaks in a ratio of about 4/3, and with RT of 7.9 and 8.4 min, respectively. The reaction mixture was filtered to remove solid materials, and the filtrate was evaporated to dryness to give a solid. The solid was dissolved in ethyl acetate, and the organic solution was extracted with a 20% ammonium chloride solution (3×40 mL). The aqueous fractions were combined (pH 6) and the pH was adjusted to 7 with a NaOH solution. The aqueous solution was then extracted with ethyl acetate (2×50 mL). The ethyl acetate fractions were combined and evaporated to dryness to give N-methyl-2-[2,2,2-trifluoro-1-(5-hydroxy-6-methyl-4-oxo-1,4-dihydro-pyridin-3-yl)-ethylamino]-propionamide as a pair of diastereoisomers (850 mg, 41% yield, HPLC Method: Column: XTerra MS C18, 4.6×250 mm; A=Aqueous phase: 4 mM Tris, 2 mM EDTA, pH 7.4; B=Organic phase: CH₃CN; Flow rate=1.0 mL/min; Injection volume=5 μL; Wavelength (λ): 220, 254, 280, 450 nm. Gradient method; min-B % 0-5, 15-55, 25-55, 25.05-5, 30-5. Apo6884, RT=7.9 min, AUC=44% at λ=280 nm, and Apo6885, RT=8.4 min, AUC=35% at λ=280 nm). Samples of the two diastereoisomers were obtained after repeated purification using the Biotage© system (C18 reverse phase cartridge; a mixture of acetonitrile and de-ionized water as eluant; gradient elution). Apo6884: 82 mg, RT=7.9 min, HPLC purity (AUC): 99% at λ=280 nm; ¹H NMR (DMSO-D₆) δ (ppm): 11.59 (br s, 1H), 7.74 (br s, 1H), 7.56 (s, 1H), 4.62 (m, 1H), 3.12 (m, 2H), 2.49 (s, 3H), 2.18 (s, 3H), 1.09 (d, J=6.3 Hz, 3H); MS-ESI m/z 308 [M+1]⁺, 249, 206 (100%), 103. Apo6885: 95 mg, RT=8.4 min, HPLC purity (AUC): 99% at λ=280 nm; ¹H NMR (DMSO-D₆) δ (ppm): 11.65 (br s, 1H), 7.67 (s, 1H), 7.63 (br s, 1H), 4.43 (m, 1H), 3.39 (m, 1H), 2.93 (m, 1H), 2.62 (d, J=4.7 Hz, 3H), 2.18 (s, 3H), 1.07 (d, J=6.9 Hz, 3H); MS-ESI m/z 308.0 [M+1]⁺, 249, 206 (100%), 103.

Example 22 Preparation of 5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one (Apo7053)

(a) To a suspension of 3-hydroxy-2-methyl-5-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (5.33 g, 23.9 mmol) and acetonitrile (50 mL) was added potassium carbonate (4.96 g, 35.9 mmol). The mixture was stirred at room temperature and iodomethane (15 mL, 239.8 mmol) was added. The progress of the reaction was monitored by HPLC (Column: XTerra MS C18, 4.6×250 mm; A=Aqueous phase: 4 mM Tris, 2 mM EDTA, pH 7.4; B=Organic phase: CH₃CN; Flow rate=1.0 mL/min; Injection volume=5 μL; Wavelength (λ): 220, 254, 280, 450 nm. Gradient method; min-B % 0-5, 15-55, 25-55, 25.05-5, 30-5.

After stirring at room temperature for 1 h, HPLC analysis of the reaction mixture indicated about 80% conversion. The reaction mixture was filtered. Both the solid and the filtrate were collected. The solid was washed with acetonitrile (40 mL×2), followed by DI water and finally with ether to give 3-hydroxy-1,2-dimethyl-5-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one. Crop 1, 1.14 g, Yield=20%.

The filtrate was combined with the acetonitrile washing solutions and concentrated to dryness to give a solid. This solid was washed with DI water and ether to give a second crop of the desired product (2.46 g, 44%). Total yield (crops 1 and 2)=64%; ¹H NMR (CD₃OD) δ (ppm): 7.79 (s, 1H), 5.43 (q, J=7.2 Hz, 1H), 3.88 (s, 3H), 2.44 (s, 3H).

(b) Thionyl chloride (7.5 mL, 102.7 mmol) was added dropwise to a suspension of 3-hydroxy-1,2-dimethyl-5-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (3.00 g, 12.7 mmol) and acetonitrile (110 mL) with external cooling using a tap water bath under a blanket of nitrogen. The progress of the reaction was monitored by TLC (eluant:methanol:dichloromethane, 1:10, v:v). After the addition of SOCl₂, a clear solution resulted, and white solid gradually formed upon further stirring. The reaction mixture was concentrated repeatedly in acetonitrile to give a solid, which was then collected and washed with acetonitrile (15 mL×2). Thus, 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-one hydrochloride, was obtained as a white solid (2.89 g). Yield=78%; ¹H NMR (DMSO-D₆) δ (ppm): 8.17 (s, 1H), 6.19 (q, J=7.5 Hz, 1H), 3.84 (s, 3H), 2.35 (s, 3H). (c) A mixture of 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-one hydrochloride (395 mg, 1.4 mmol) and acetonitrile (30 mL) was added to a 40 wt % dimethylamine in water (3.5 mL, 27.7 mmol). The resulting yellowish solution was stirred vigorously, and the progress of the reaction was monitored by TLC (eluant: methanol/dichloromethane, 1/10, v/v). The starting material was completely consumed within 5 min. The reaction mixture was concentrated to give a solid. The solid was dissolved in dichloromethane (30 mL), which was then washed with a 10% ammonium chloride solution (15 mL×2). The organic phase was dried over sodium sulfate, filtered, and concentrated to give 5-[1-(dimethylamino)-2,2,2-trifluoroethyl]-3-hydroxy-1,2-dimethylpyridin-4(1H)-one (Apo7053) as a solid product (200 mg). Yield=56%; HPLC Method 1, RT=10.2 min, HPLC purity (AUC): 98.3% at 280 nm); ¹H NMR (DMSO-D₆) δ (ppm): 7.68 (s, 1H), 4.86 (q, J=10.1 Hz, 1H), 3.73 (s, 3H), 2.29 (s, 3H), 2.23 (s, 6H). MS-ESI m/z 265 [M+1]⁺, 220 (100%), 192.

In a similar manner, the following compounds were prepared:

(i) 3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(piperidin-1-yl)ethyl]pyridin-4(1H)-one (Apo7054) was prepared from the reaction of 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-one hydrochloride (304 mg, 1.0 mmol) and piperidine (2.0 mL, 20.3 mmol). The reaction was completed within 20 min, and Apo7054 was obtained as a solid product (232 mg). Yield=73%; HPLC Method 1, purity (AUC)=99.4% at 280 nm; ¹H NMR (DMSO-D₆) δ (ppm): 7.66 (s, 1H), 4.83-4.94 (m, 1H), 3.71 (s, 3H), 2.56 (m, 2H), 2.41 (m, 2H), 2.27 (s, 3H), 1.46 (br, 4H), 1.28 (br, 2H); MS-ESI m/z 305 [M+1]⁺ (100%), 220. (ii) 3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(1H-imidazol-1-yl)ethyl]pyridin-4(1H)-one (Apo7055) was prepared from 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-one hydrochloride (505 mg, 1.7 mmol) and imidazole (3.5 g, 51.4 mmol). The reaction was stopped when analysis of the HPLC chromatogram (Method 1) of the reaction mixture indicated higher than 98% conversion. The reaction mixture was concentrated to give a solid. The solid was dissolved in de-ionized water (4 mL), and the pH of the solution was adjusted to 6.5 with a 6.00 N hydrochloric acid solution. The resulting solution was repeatedly extracted with dichloromethane (15 mL×4, 30 mL×2). The organic fractions were combined, dried over sodium sulfate, filtered, and concentrated. The desired compound Apo7055 was obtained as a solid from dichloromethane (320 mg). Yield=64%; HPLC purity (AUC): 99.7% at 280 nm); ¹H NMR (DMSO-D₆) δ (ppm): 8.15 (s, 1H), 7.98 (s, 1H), 7.52 (s, 1H), 6.96 (s, 1H), 6.66 (q, J=9.1 Hz, 1H), 3.76 (s, 3H), 2.29 (s, 3H). MS-ESI m/z 288 [M+1]⁺, 220 (100%). (iii) 3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(methylamino)ethyl]pyridin-4(1H)-one (Apo7056) was prepared from 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-one hydrochloride (400 mg, 1.4 mmol) and methylamine (3.0 mL, 34.4 mmol). The reaction was essentially completed within 15 min. The reaction mixture was concentrated to give a solid. A sample of salt free Apo7056 product was obtained by purification using the Biotage© instrument (C18 reversed phase; eluant: water and acetonitrile; gradient, 100:0 to 100:4). (48 mg). HPLC Method 1, RT=8.52 min, HPLC purity (AUC): 99.3% at 280 nm); ¹H NMR (CD₃OD) δ (ppm): 7.77 (s, 1H), 4.58 (q, J=8.0 Hz, 1H), 3.80 (s, 3H), 2.44 (s, 3H), 2.35 (s, 3H). MS-ESI (m/z) 251.2 [M+1]⁺, 220.2 (100%). (iv) 3-Hydroxy-1,2-dimethyl-5-[2,2,2-trifluoro-1-(4-methylpiperazin-1-yl)ethyl]pyridin-4(1H)-one hydrochloride (Apo7063) was prepared from 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,2-dimethylpyridin-4(1H)-one hydrochloride (550 mg, 1.9 mmol) and 1-methylpiperazine (3.0 mL, 27.0 mmol) was added. The reaction was stopped when analysis of the HPLC chromatogram (Method 1) of the reaction mixture complete conversion. The reaction mixture was concentrated to give a solid. To the solid was added methanol (2 mL), the mixture was vortexed and filtered. Thus, Apo7063 was obtained as a solid (280 mg). Yield=41%; HPLC Method 1, purity (AUC)=99.8% at 280 nm; ¹H NMR (DMSO-D₆+a few drops of D₂O) δ (ppm): 7.69 (s, 1H), 4.93 (q, J=9.7 Hz, 1H), 3.70 (s, 3H), 2.60-3.40 (b, 8H), 2.69 (s, 3H), 2.29 (s, 3H); MS-ESI m/z 320 [M+1]⁺ (100%), 220.

Example 23 Preparation of 2-(dimethylamino)-3-hydroxy-1-methyl-6-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo7077)

Thionyl chloride (1.6 mL, 21.9 mmol) was added dropwise to a suspension of 5-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (0.82 g, 3.7 mmol) and acetonitrile (30 mL) under a blanket of nitrogen. The reaction was heated to reflux and a clear solution resulted. The progress of the reaction was monitored by TLC (eluant:methanol:dichloromethane, 1:10, v:v). The reaction mixture was concentrated repeatedly in acetonitrile to give a solid, which was used in the next step without further purification. ¹H NMR (DMSO-D₆) δ (ppm): 8.35 (s, 1H), 7.62 (s, 1H), 6.77 (m, 1H), 4.12 (s, 3H).

A solution of the chloride product from the previous step in acetonitrile was added to a solution of dimethylamine (40 wt % in water, 9.0 mL, 71.1 mmol). The mixture was stirred vigorously. The progress of the reaction was monitored by TLC (eluant: methanol/dichloromethane, 1/10, v/v), and by HPLC (Method 1, RT of Apo7077=13.37 min, conversion was about 78%). The reaction mixture was concentrated to dryness. The residue was taken up in dichloromethane (30 mL), then washed with de-ionized water. The organic phase was dried over sodium sulfate, filtered, and concentrated to give a crude solid. Purification of the crude by column chromatography on silica gel (eluant: methanol/dichloromethane, 5/100, v/v) afforded Apo7077 (280 mg). Yield=30%; HPLC purity (AUC): 99.2% at 280 nm; ¹H NMR (DMSO-D₆) δ (ppm): 6.23 (s, 1H), 3.93 (q, J=10.7 Hz, 2H), 3.63 (s, 3H), 2.74 (s, 6H); ¹⁹F NMR (DMSO-D₆) δ (ppm): −63.37 (t, J=50.8 Hz); MS-ESI m/z 251 [M+1]⁺ (100%), 236, 221, 207, 166.

Example 24 Preparation of 2-((dimethylamino)methyl)-3-hydroxy-1-methyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (Apo7081)

Thionyl chloride (0.48 mL, 6.6 mmol) was added dropwise to a suspension of 3-hydroxy-2-(hydroxymethyl)-1-methyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.50 g, 5.9 mmol) in acetonitrile (45 mL). The progress of the reaction was monitored by TLC (eluant:methanol:dichloromethane, 15:100, v:v), and the starting material was consumed within 5 min. The reaction mixture was concentrated repeatedly in acetonitrile to give a solid, which was then washed with acetonitrile (15 mL×1). Thus, 2-(chloromethyl)-3-hydroxy-1-methyl-6-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one hydrochloride was obtained as a white solid (1.18 g).

The latter compound was dissolved in acetonitrile (20 mL) and added to a solution of dimethylamine (40 wt % in water, 15 mL, 118.5 mmol). The resulting yellowish solution was stirred vigorously, and the progress of the reaction was monitored by HPLC Method: Column: XTerra MS C18, 4.6×250 mm; A=Aqueous phase: 4 mM Tris, 2 mM EDTA, pH 7.4; B=Organic phase: CH₃CN; Flow rate=1.0 mL/min; Injection volume=5 μL; Wavelength (λ): 220, 254, 280, 450 nm. Gradient method; min-B % 0-5, 15-55, 25-55, 25.05-5, 30-5. (RT of Apo7081=9.45 min, HPLC purity (AUC): about 60% at λ=280 nm). The reaction mixture was concentrated to give a solid. To the solid was added de-ionized water (15 mL) and methanol (100 mL), the resulting mixture was stirred and filtered. The filtrate was collected and concentrated in vacuo. The residue was purified by column chromatography on silica gel (eluant: methanol/dichloromethane, 5/100, v/v). Thus, Apo7081 was obtained (24 mg). HPLC Method 1, RT=9.59 min, purity (AUC): 98.6% at 280 nm; ¹H NMR (CD₃OD) δ (ppm): 6.82 (s, 1H), 5.54 (q, J=6.2 Hz, 1H), 3.96 (s, 3H), 3.76 (s, 2H), 2.32 (s, 6H); MS-ESI m/z 281 [M+1]⁺, 236 (100%), 208.

Example 25 Preparation of 5-hydroxy-1-methyl-2-(2,2,2-trifluoro-1,1-dihydroxyethyl)pyridin-4(1H)-one (Apo7072)

(a) To an ice-salt cooled suspension of 5-(benzyloxy)-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.20 g, 3.8 mmol) and a 10% sodium bicarbonate solution (4 mL) in acetone (36 mL) were placed in a 250-mL 1-N RB equipped with a magnetic stir bar to give a suspension was added a solution of potassium bromate (99 mg, 0.6 mmol) dissolved in de-ionized water (3 mL). A solution of TEMPO (31 mg, 0.2 mmol) in acetone (1 mL) was added to the suspension, followed by a solution of sodium hypochlorite (0.96 M, 6.5 mL, 6.24 mmol). HPLC was used to monitor the progress of the reaction (HPLC Column: XTerra MS C18, 4.6×250 mm; A=Aqueous phase: 4 mM Tris, 2 mM EDTA, pH 7.4; B=Organic phase: CH₃CN; Flow rate=1.0 mL/min; Injection volume=5 μL; Wavelength (λ): 220, 254, 280, 450 nm. Isocratic method; aqueous:organic=75:25, RT of the SM=10.30 min, RT of the product=11.37 min, the conversion was >99%). The reaction mixture was filtered. The filtrate was collected and concentrated to give a semi-solid. The semi-solid was suspended in dichloromethane (40 mL) and brine (30 mL). The mixture was stirred and the solid was collected by suction filtration. The solid was washed with de-ionized water (15 mL×4) and with ether (15 mL×4). Thus, 5-(benzyloxy)-1-methyl-2-(2,2,2-trifluoro-1,1-dihydroxyethyl)pyridin-4(1H)-one was obtained (0.93 g). Yield=73%; HPLC Method 2, purity (AUC)=99.4% at 280 nm; ¹H NMR (DMSO-D₆) δ (ppm): 8.45 (s, 2H), 7.67 (s, 1H), 7.4 (m, 5H), 6.66 (s, 1H), 5.04 (s, 2H), 3.85 (s, 3H); MS-ESI m/z 330 [M+1]⁺, 91 (100%). (b) Debenzylation of 5-(benzyloxy)-1-methyl-2-(2,2,2-trifluoro-1,1-dihydroxyethyl)pyridin-4(1H)-one (700 mg, 2.1 mmol) was carried out in a hydrochloric acid solution (4M, 22 mL) by heating to reflux. HPLC was used to monitor the progress of the reaction (HPLC Method 2, RT of the SM=11.47 min, RT of the product=3.26 min, conversion >98%). The resulting solution was concentrated to give oil. About half of the oily residue was weighed out, and dissolved in de-ionized water. The pH of the resulting solution was adjusted to 6 with a 6.00 N sodium hydroxide solution (160 μL). Solid appeared upon stirring. The solid was collected by filtration, thoroughly washed with de-ionized water and ether. Thus, a sample of 5-hydroxy-1-methyl-2-(2,2,2-trifluoro-1,1-dihydroxyethyl)pyridin-4(1H)-one (Apo7072) was obtained (118 mg). Yield=46%; HPLC Method: Column: XTerra MS C18, 4.6×250 mm; A=Aqueous phase: 4 mM Tris, 2 mM EDTA, pH 7.4; B=Organic phase: CH₃CN; Flow rate=1.0 mL/min; Injection volume=5 μL; Wavelength (λ): 220, 254, 280, 450 nm. Isocratic method; aqueous:organic=75:25, purity (AUC)=99.5% at 280 nm; ¹H NMR (DMSO-D₆+a few drops of D₂O) δ (ppm): 7.47 (s, 1H), 6.66 (s, 1H), 3.82 (s, 3H); MS-ESI m/z 240 [M+1]⁺, 222 (100%), 125.

Example 26

A. pKa Determination by Potentiometric Titration

The pKa values of ligands were determined by potentiometric titration when a ligand concentration >1×10⁻² M in water could be prepared. In a typical experiment, the sample solution (1.00×10⁻² M) was prepared by the following method: Apo7041 (125.4 mg) was weighed into a 50 mL volumetric flask, and about 40 mL of 0.1 M NaCl was added. The mixture was sonicated for 10 min to give a clear colorless solution. More of the 0.1 M NaCl was added to volume and the resulting solution was vortexed to mix. 40 mL of the solution was transferred into a T70 titration cell by using a 10 mL digital pipet A 6.000 N sodium hydroxide solution (127 μL, 1.9 equiv) was added, and the pH (11.82) of the solution was recorded. The solution was allowed to equilibrate at 22° C. for 5 min.

The solution was then titrated against a 6.000 N hydrochloric acid solution at 22° C. by using a Mettler Toledo T70 autotitrator, until the pH reached 1.5. The volume of acid added and the pH reading were recorded. Thus, 501 measurements were taken for this experiment.

The data set of pH vs. acid volume was analyzed using Hyperquad 2000 software (version 2.1, Peter Gans, University of Leeds). The pKa values were obtained using the model: L⁻+H⁺⇄LH (pKa₁), LH+H⁺⇄LH₂ ⁺, and LH₂ ⁺+H⁺⇄LH₃ ²⁺ (pKa₃). Thus, Apo7041 has pKa₁=9.39, pKa₂=3.52, and pKa₃=1.66 as determined potentiometrically.

B. pKa Determination by Spectrophotometric Titration

The pKa values of ligands can be determined by spectrophotometric titration when both the conjugated acid and base absorb in the UV-visible region. In a typical experiment, the sample solution was prepared by the following method: Apo7041 stock solution (12.74 mg) was weighed into a 10 mL volumetric flask, and 0.1 M NaCl solution was added to volume. The mixture was sonicated and voltexed to give a clear colorless solution. The concentration of Apo7041 of this stock solution is 5.1×10⁻³ M.

Apo7041 sample solution: 727 μL of the above stock solution was transferred into a 50 mL volumetric flask by using a 1000 μL digital pipet, and 0.1 M NaCl was added to volume. The resulting solution was vortexed to mix to give a sample solution. The concentration of Apo7041 of this sample solution is 7.4×10⁻⁵ M. 20 mL of the sample solution was transferred into a 35 mL beaker by using a 10 mL digital pipet. The sample solution was circulated between the beaker and the flow cell using a sipper system.

The sample solution was titrated against standard hydrochloric acid solutions at 22° C. to reach pH 1.11. After each addition of acid the solution was allowed to equilibrate until a constant pH reading was reached. The pH and the UV-Vis spectrum were recorded for each measurement. The solution was titrated until there was no obvious change in the spectra after several subsequent additions of acid. Thus, 30 measurements were recorded.

The resulting data set was then analyzed using pHAB (Peter Gans, University of Leeds). The pKa values were obtained using the model: LH+H⁺⇄LH₂ ⁺, and LH₂ ⁺+H⁺⇄LH₃ ²⁺ (pKa₃). Thus, Apo7041 has pKa₂=3.51, and pKa₃=1.23 as determined spectrophotometrically.

Example 27

Stoichiometry of Fe-Complexes by Job's Method

In a typical experiment Fe-Apo7053 complex solutions were prepared by mixing a stock solution of Fe²⁺ (atomic absorption standard, 989 μg/mL in 1 wt % HCl, Aldrich) and a stock solution of Apo7053 (7.88×10⁻³ M in 0.1 M MOPS, pH 7.4). Twelve sample solutions were prepared. While the sum of the total iron concentration ([iron]_(total)) and the total ligand concentration ([L]_(total)) in each of the 12 sample solutions were kept constant (8.00×10⁻⁴ M), the molar fraction of the ligand, α (α=[L]_(total)/([L]_(total)+[iron]_(total))), for the 12 sample solutions were different, and were prepared as 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.75, 0.8, 0.9 and 1.0, respectively. The total volume for each of the 12 sample solutions was 5 mL, using MOPS (0.1 M, pH 7.4) as the solvent. The pH of the 12 solutions were adjusted to pH 7.4 with NaOH. The sample solutions were vortexed at rt for 2.5 h, and then stayed at rt overnight. The sample solutions were centrifuged at 4000 rpm for 15 min. The UV-Vis spectrum was recorded at 22° C. for each of the 12 solutions.

A Job's plot was created with the absorbance at 458 nm as the y-axis and α as the x-axis. A maximum absorbance was found at α=0.75, which corresponds to an iron:ligand ratio of 1:3 in the complexes. The Job's plot result is shown in FIG. 3A.

Proceeding in a similar manner, the Job's plot for Fe-Apo7041 was created, and is shown in FIG. 3B.

Example 28

Distribution Coefficient Determination, D_(7.4)

K₂HPO₄ buffer (50 mM, pH=7.4) and 1-octanol were used as the aqueous phase and the organic phase, respectively. The K₂HPO₄ buffer and 1-octanol were mixed, and pre-saturated with each other before use.

In a typical experiment, an aqueous solution of Apo6995 (3-hydroxy-2-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one) was prepared by weighing out 3 mg of the compound into a 10-mL test-tube. It was then mixed with K₂HPO₄ buffer (2 mL) and sonicated for 30 minutes with frequent vortexing. The solution was then filtered through HPLC syringe filter (4 mm PVDF syringe filter 0.45 μM) to obtain the aqueous solution. It was analyzed by HPLC (Column: Waters Symmetry C₁₈, 5 μM, 3.9×50 mm; Mobile phase: 0.035% HClO₄/ACN; Gradient method: time in minutes—ACN in %: 0-10, 10-90, 12-90, 14-10, 16-10; Flow rate: 1 mL/min; Injection volume=2 μL; detector wavelength: 270 nm) to obtain the peak height (H_(I)).

One mL of this aqueous solution was pipetted out into another 10-mL test-tube and mixed with 1 mL of 1-octanol. The mixture was then vortexed for 1 hour. The solution was centrifuged at 2000 rpm for 10 minutes. A small amount of the lower aqueous layer was carefully pipetted out and analyzed by HPLC to obtain the peak height (H_(F)). The distribution coefficient, D_(7.4), was calculated using the following equation: D_(7.4)=(H_(I)−H_(F))/H_(F).

In a similar fashion, D_(7.4) was determined for the following compounds:

Apo# D_(7.4) Log D_(7.4) Deferiprone 0.17 −0.77 6995 2.51 0.40 7030 5.93 0.77 7040 8.76 0.94 7060 4.93 0.69 7065 4.93 0.69 7066 4.69 0.67 7067 2.82 0.45 7069 0.66 −0.18 7070 1.72 0.23 7083 1.70 0.23

Example 29

Determination of Metal Complexation Constants

A. Instrumental and Chemicals:

For spectrophotometric titration, a pH meter (Accumet Research AR15, 13-636-AR15, Fisher) and a combination electrode (Accumet Standard-size Glass Combination Electrode, 13-620-285, Fisher) were used for pH measurements. Before using, the electrode was calibrated with three standard buffer solutions (pH 4.00, pH 7.00, and pH 10.00, Fisher). The titrant was added manually by using digital pipettes (Eppendorf). An UV-visible spectrophotometer (Agilent 8453) was used for UV-Vis absorbance measurements.

A sipper system (89068D Agilent) was used whenever pH-dependent absorbencies were measured. A vortexer (VX-2500 Multi-tube Vortexer, VWR Scientific Products) was used for the preparation of sample solutions in both distribution coefficient and Job's plot experiments.

For potentiometric titration, an autotitrator (Mettler Toledo T70) and a combination electrode (Mettler Toledo DG 115-SC) were used. Before using, the electrode was calibrated with three standard buffer solutions (pH 4.00, pH 7.00, and pH 10.00, Fisher). The titrant was added automatically by using T70. The data set of pH vs. titrant volume was recorded.

The metal stock solutions were purchased from Aldrich: Iron atomic absorption standard solution (1000 μg/ml of Fe in 1 wt. % HCl); Aluminum atomic absorption standard solution (1000 μg/ml of Al in 1 wt % HCl); Calcium atomic absorption standard solution (1000 μg/ml of Ca in 1 wt. % HCl); Copper atomic absorption standard solution (1000 μg/ml of Cu in 1 wt. % HNO₃); Magnesium atomic absorption standard solution (1000 μg/ml of Mg in 1 wt. % HNO₃); Manganese atomic absorption standard solution (1000 μg/ml of Mn in 1 wt. % HNO₃); Zinc atomic absorption standard solution (1000 μg/ml of Zn in 1 wt. % HCl). The standard Sodium Hydroxide and Hydrochloric acid solutions were purchased from VWR Scientific Products. MOPS (3-[N-Morpholino]propanesulfonic acid) was purchased from Sigma-Aldrich.

B. Determination of Stepwise Formation Constants for Fe-Apo7041 System by Spectrophotometric Titration in 0.1M NaCl Solution

Stepwise formation constants for M^(n+)-ligand systems were determined by spectrophotometric titration when metal complexes have a strong absorbance in the visible region due to ligand to metal charge transfer.

In a typical experiment, the sample solution was prepared according to the following procedure: compound Apo7041 (12.96 mg) was weighed into a 50 mL volumetric flask, and about 40 mL of 0.1 M NaCl was added. The mixture was sonicated for 10 min to give a clear colorless solution. The iron stock solution (atomic absorption standard, Aldrich, 565 μL, 10.00 μmol) was pipetted into the solution, followed by the addition of 1.000 N NaOH (170 μL). More of the 0.1 M NaCl was added to volume and the resulting solution was vortexed to mix. The molar ratio between the total iron and the total Apo7041 was 1/5.1. The mixture was vortexed at rt for 1 h. 20 mL of the sample solution was transferred into a 35 mL beaker by using a 10 mL digital pipet. The sample solution was circulated between the beaker and the flow cell using a sipper system. The sample solution was titrated against hydrochloric acid solutions at 22° C. until the pH reached 0.021. After each addition of acid, the solution was allowed to equilibrate until a constant pH reading was reached. The pH and the UV-Vis spectrum were recorded for each measurement. For each measurement enough acid was added so that there was a slight decrease in the absorbance of the spectrum. Altogether, 68 measurements were taken to finish the experiment.

The resulting data set was then analyzed using pHAB. The formation constants for Fe-Apo7041 system were optimized using the model shown in the first column of the table. The results are shown in the Table 29B below.

TABLE 29B The model symbol value Fe³⁺ + LH ⇄ (FeLH)³⁺ Log β₁₁₁ 18.1 (FeLH)³⁺ + LH ⇄ (FeL₂H₂)³⁺ Log β₁₂₂ 35.0 (FeL₃H₂)²⁺ + H⁺ ⇄ (FeL₃H₃)³⁺ Log β₁₃₃ 50.5 (FeL₃H)⁺ + H⁺ ⇄ (FeL₃H₂)²⁺ Log β₁₃₂ 48.3 (FeL₃)⁰ + H⁺ ⇄ (FeL₃H)⁺ Log β₁₃₁ 44.5 Fe³⁺ + 3L⁻ ⇄ (FeL₃)⁰ Log β₁₃₀ 38.8 L⁻ + H⁺ ⇄ LH pKa₁ 9.39 LH + H⁺ ⇄ LH₂ ⁺ pKa₁ + pKa₂ 12.91 LH₂ ⁺ + H⁺ ⇄ LH₃ ²⁺ pKa₁ + pKa₂ + pKa₃ 14.57 C. Determination of Stepwise Formation Constants for Cu-Apo7041 System by Potentiometric Titration in 0.1M Aqueous NaCl/MeOH, 1/1, v/v Mixture

Stepwise formation constants for Cu²⁺-ligand system were determined by potentiometric titration when metal complexes (≥0.002 M) do not precipitate during titration. In a typical experiment, the sample solution was prepared by the following method: Apo7041 (126.1 mg, 0.50 mmol) was weighed into a 50 mL volumetric flask, and about 35 mL of a mixed solvent (0.1 M NaCl aqueous:MeOH, 1:1, v:v) was added. The mixture was sonicated for 10 min to give a clear colorless solution. The copper stock solution (atomic absorption standard, Aldrich, 6.33 mL, 0.10 mmol) was pipetted into the solution. More of the mixed solvent was added to volume and the resulting solution was vortexed to mix. The molar ratio between the total copper and the total Apo7041 was 1/5. 40 mL of the solution was transferred into a T70 titration cell by using a 10 mL digital pipet. A 6.000 N sodium hydroxide solution (300 μL) was added, and the pH (12.17) of the solution was recorded. The solution was allowed to equilibrate at 22° C. for 5 min.

The solution was then titrated against a 6.000 N hydrochloric acid solution at 22° C. by using a Mettler Toledo T70 autotitrator, until the pH reached 1.5. The volume of acid added and the pH reading were recorded. Thus, 533 measurements were taken for this experiment.

The pKa values of Apo7041 in the same mixed solvent were also determined by potentiometric titration using the procedure described in Example 1.

The data set of pH vs. acid volume for Cu-Apo7041 system was analyzed using Hyperquad 2000 software (version 2.1, Peter Gans, University of Leeds). The formation constants for Cu-Apo7041 system were optimized using the model shown in the first column of Table 29C. The results are shown in the second and third column.

TABLE 29C The model symbol value (CuL₂H)⁺ + H⁺ ⇄ (CuL₂H₂)²⁺ Log β₁₂₂ 27.9 (CuL₂)⁰ + H⁺ ⇄ (CuL₂H)⁺ Log β₁₂₁ 23.0 Cu²⁺ + 2L⁻ ⇄ (CuL₂)⁰ Log β₁₂₀ 17.3 L⁻ + H⁺ ⇄ LH pKa₁ 10.1 LH + H⁺ ⇄ LH₂ ⁺ pKa₁ + pKa₂ 13.3 LH₂ ⁺ + H⁺ ⇄ LH₃ ²⁺ pKa₁ + pKa₂ + pKa₃ 15.3 D. Determination of Stepwise Formation Constants for Zn-Apo7041 System by Potentiometric Titration in 0.1M Aqueous NaCl/MeOH, 1/1, v/v Mixture

Stepwise formation constants for Zn²⁺-ligand system were determined by potentiometric titration when metal complexes (≥0.002 M) do not precipitate during titration. In a typical experiment, the sample solution was prepared by the following method: Apo7041 (126.3 mg, 0.50 mmol) was weighed into a 50 mL volumetric flask, and about 35 mL of a mixed solvent (0.1 M NaCl aqueous:MeOH, 1:1, v:v) was added. The mixture was sonicated for 10 min to give a clear colorless solution. The zinc stock solution (atomic absorption standard, Aldrich, 6.64 mL, 0.10 mmol) was pipetted into the solution followed by addition of sodium hydroxide solution (6.000 N, 300 μL). More of the mixed solvent was added to volume and the resulting solution was vortexed to mix. The molar ratio between the total zinc and the total Apo7041 was 1/5. 40 mL of the solution was transferred into a T70 titration cell by using a 10 mL digital pipet. A 6.000 N sodium hydroxide solution (160 μL) was added, and the pH (11.95) of the solution was recorded. The solution was allowed to equilibrate at 22° C. for 5 min.

The solution was then titrated against a 6.000 N hydrochloric acid solution at 22° C. by using a Mettler Toledo T70 autotitrator, until the pH reached 1.5. The volume of acid added and the pH reading were recorded. Thus, 523 measurements were taken for this experiment.

The data set of pH vs. acid volume for Zn-Apo7041 system was analyzed using Hyperquad 2000 software (version 2.1, Peter Gans, University of Leeds). The formation constants for Zn-Apo7041 system were optimized using the model shown in the first column of the table 29D. The results are shown in the second and third column.

TABLE 29D The model symbol value Zn²⁺ + LH ⇄ (ZnLH)²⁺ Log β₁₁₁ 13.1 (ZnL₂)⁰ + H⁺ ⇄ (ZnL₂H)⁺ Log β₁₂₁ 19.6 Zn²⁺ + 2L⁻ ⇄ (ZnL₂)⁰ Log β₁₂₀ 13.2 L⁻ + H⁺ ⇄ LH pKa₁ 10.1 LH + H⁺ ⇄ LH₂ ⁺ pKa₁ + pKa₂ 13.3 LH₂ ⁺ + H⁺ ⇄ LH₃ ²⁺ pKa₁ + pKa₂ + pKa₃ 15.3 Calculation of pM^(n+)

pM^(n+) is defined as −log [M(H₂O)_(m)]^(n+) at physiological conditions, i.e.: pH 7.4, a ligand concentration of 10 μM, and a metal concentration of 1 μM. To calculate pM^(n+) for a ML_(n) system, β_(n) and pKa values are needed (β_(n) are the formation constants for M^(n+)+n L⁻⇄ML_(n); pKa are the equilibrium constants for L⁻+n H⁺⇄LH_(n) ^((n-1)+)). The pM^(n+) is calculated using the HySS software (HYSS© 2000 Protonic Software).

The data obtained from the above determinations for Apo7041, a compound of formula I, can be found in Table 1.

Example 30

Cyclic Voltammetry

A criterion in the design of compounds of formula I concerns controlling the redox potential of the Fe-chelate system at pH 7.4 to a negative value below −320 my (vs NHE) to prevent any reactions with oxygen species. Iron exists in multiple states including Fe²⁺ and Fe³⁺. The iron (II)/iron (III) pair can act as a pair of one electron reducing agent and oxidizing agent. According to Crumbliss (http://www.medicine.uiowa.edu/FRRB/VirtualSchool/Crumbliss-Fe.pdf) and Pierre (BioMetals, 12, 195-199, 1999), selective chelation of iron with redox potential control is a means to prevent iron from participating in a catalytic cycle to produce toxic hydroxyl radicals and/or reactive oxygen species (ROS) (e.g. via the Fenton reaction or Haber Weiss cycle). The Fe (III)-tris-chelate system with redox potential below −320 my (vs NHE or −540 my vs Ag/AgCl) at pH 7.4 will not be reduced by any biological reducing agents such as NADPH/NADH, therefore it will not participate in the Haber Weiss cycle to generate ROS (reactive oxygen species). Within the mammalian body, iron is bound to different proteins such as transferrin in human blood to ensure it remains in a form that cannot react with any oxygen molecules. The E_(1/2) value of Fe-transferrin is −500 my (vs. NHE or −720 my vs. Ag/AgCl).

The redox potential of iron complexes can be measured by cyclic voltammetry (CV). The use of CV to measure the redox potentials of iron chelates deferiprone, deferrioxamine and Apo7041 (a representative compound of this invention) as chelators respectively, is illustrated in FIG. 1. Iron chelates such as Fe-desferrioxamine (DFO) and Fe-(deferiprone)₃ have redox potential E_(1/2) values at −480 my (vs. NHE) and −628 my (vs. NHE), respectively, at pH 7.4. Compounds of formula I such Fe(Apo7041)₃ has a E_(1/2) value of −530 my (vs. NHE) slightly more negative when compared to that of desferrioxamine. The cyclic voltammogram of Fe-DFO, Fe(deferiprone)₃ and Fe(Apo7041)₃ can be found in FIG. 1. One advantage of the chelators of this invention is that the redox potentials of their iron chelates lie in the extreme negative range at physiological pH 7.4, therefore their iron chelates will not participate in the redox cycle to generate reactive oxygen species at physiological pH. When combined with other novel properties as described in this invention, the compounds of formula I are effective agents in the removal of iron via a chelation mechanism.

Determination of E_(1/2) of Fe(Apo7041)₃

A. Materials and Instruments

Potassium ferricyanide (III) was purchased from Aldrich. Deferoxamine mesylate (DFO) was purchased from Sigma. Iron atomic absorption standard solution (contains 1000 μg/mL of Fe in 1 wt. % HCl) was purchased from Aldrich. Electrochemical measurements were performed with a cyclic voltammetric analyzer (BAS, CV-50W Potentiostat). Software BAS CV-50W Version 2.31 was used. The following electrodes were used for determining redox potentials of the iron complexes: Ag/AgCl reference electrode (BAS, MF-2052); platinum auxiliary electrode (BAS, MW-1032); and glassy carbon working electrode (BAS, MF-2012). A pH meter (Accumet Research AR15, 13-636-AR15, Fisher Scientific) and pH electrode (AccupHast combination electrode, 13-620-297, Fisher Scientific) were used for pH adjustment of the sample solutions.

B. Preparation of Sample Solutions

2.0 mM solution of Fe(DFO) in 0.1 M NaCl (pH 7.4) 148.1 mg of deferoxamine mesylate (purity=95%) was accurately weighed out into a 100-mL volumetric flask. The solid was dissolved in about 30 mL of 0.1 M NaCl to give a clear colorless solution. To the solution was added 11.114 mL of the standard iron solution. The solution was diluted with 0.1 M NaCl to the 100 ml mark in the volumetric flask. The resulting solution was vortexed to ensure complete mixing. The solution was transferred to a 200-mL beaker. The pH of the solution was then adjusted to about 7.1 by adding standard solutions of sodium hydroxide. The beaker was then covered with parafilm and the solution was left stirring for overnight. The pH of the solution was adjusted to 7.40 in the following test day. The calculated molar ratio between iron_(total) and DFO_(total) was 1:1.07.

1.0 mM solution of Fe(Apo7041)₃ in 0.1 M NaCl (pH 7.4) Apo7041 (19.8 mg, 0.079 mmol) was accurately weighed out into a 25-mL round bottom flask. The solid was dissolved in about 14 mL of 0.1 M NaCl to give a clear colorless solution. To the solution was added a standard iron solution (847 μL, 0.015 mmol) followed by addition of sodium hydroxide solution (6.000 N, 44 μL). The resulting solution was vortexed to ensure complete mixing. The pH of the solution was recorded (7.5). The calculated molar ratio between iron_(total) and Apo7041_(total) was 1/5.3. In a similar manner, a solution of 2.0 mM of Fe(deferiprone)₃ in 0.1 M NaCl (pH 7.4) was prepared.

C. Determination of Redox Potentials of Iron Complexes

All potentials in the text are given versus the Ag/AgCl reference electrode. The redox potentials of 2.0 mM of K₃Fe(CN)₆ in 1.0 M potassium nitrate were measured at the beginning of each working day to verify the proper functioning of the cyclic voltammeter. The redox peak potentials of solutions of iron complexes at pH 7.4, that is, Fe(DFO), Fe(deferiprone)₃, and Fe(Apo7041)₃, were determined. For example, the Fe(Apo7041)₃ sample solution was purged with argon for approximately 15 min. A solvent trap containing 0.1 M NaCl was used to reduce evaporation. Cyclic voltammograms of the sample solution were recorded using glassy carbon electrode (working electrode), Ag/AgCl electrode (reference electrode), and platinum electrode (auxiliary electrode). The following instrument parameters were used: Init E (mV)=0; High E (mV)=0; Low E (mV)=−1200; Init P/N=N; V (mV/s)=200; No. of Sweep Segments=3; Sensitivity (μA/V)=100; Stir Speed=50 rpm.

FIG. 1 shows the cyclic voltammograms of iron(III)L_(n) complexes at pH 7.4: a) Fe(Apo7053)₃; b) Fe(Apo7041)₃, c) Fe(Apo7069)₃. The reduction peak potential (E_(p) ^(red)), the oxidation peak potential (E_(p) ^(ox)), the absolute difference (ΔE_(p)) between E_(p) ^(red) and E_(p) ^(ox), and redox potential (E_(1/2)) of the four iron complexes were measured. E_(1/2) value is calculated as (E_(p) ^(red)+E_(p) ^(ox))/2.

The cyclic voltammograms of a) Fe(Apo7053)₃; b) Fe(Apo7041)₃; c) Fe(Apo7069)₃ represent a reversible single electron transfer process for each complex: Fe(III)L_(n)/Fe(II)L_(n). The E_(1/2) value of the reference Fe(DFO) determined in this lab is −698 mV versus the Ag/AgCl reference electrode, which is in excellent agreement to literature value (−688 mV) (A. L. Crumbliss et al., Inorganic Chemistry, 2003, 42, 42-50). The E_(1/2) value of Fe(Apo7041)₃ is −731 mV, which is slightly more electronegative than that of Fe(DFO).

The Electrochemical properties of iron(III)L_(n) complexes in 0.1M aqueous NaCl at pH 7.4 are listed below. Fe(DFO), {DFO=deferioxamine B}; Fe(L1)₃, {L1=deferiprone}; K₃Fe(CN)₆ are used as controls for the validation of the study.

E_(red) E_(ox) E_(1/2) (mV) vs. E_(1/2) (mV) complex (mV) (mV) ΔE (mV) Ag/AgCl vs. NHE K₃Fe(CN)₆ 197 282 85 +20 +240 FeDFO −754 −642 112 −698 −478 Fe(L1)₃ −841 −752 89 −797 −577 Fe(7041)₃ −789 −672 117 −731 −511 Fe(7053)₃ −856 −761 95 −809 −589 Fe(7069)₃ −793 −706 87 −750 −530

Example 31

Benzoic Acid Hydroxylation Assay

Benzoic acid is a hydroxyl radical scavenger and reacts with hydroxyl radical to give 2-hydroxy, 3-hydroxy and 4-hydroxybenzoic acids. The benzoic acid hydroxylation assay is a chemical assay designed to detect damage caused by hydroxyl radical (Dean and Nicholson, Free Radical Research 1994, vol 20, 83-101). For example, deferiprone suppresses the formation of hydroxybenzoic acids in the presence of iron salts and hydrogen peroxide, while EDTA and iron salts allow such hydroxylation reactions to take place.

This screening assay involves the use of iron salt, benzoic acid, hydrogen peroxide and the chelator and measures the ability of the chelator to inhibit the formation of hydroxybenzoate as an indicator to prevent hydroxyl radical formation in living system.

Compound of formula I has similar properties to deferiprone and suppresses the formation of the hydroxybenzoic acid when benzoic acid is treated with hydrogen peroxide and iron salts. The results are shown in FIG. 9. Compounds of formula I show inhibitory effect to the hydroxyl radical transformation of benzoic acid. Thus, these compounds are protective towards hydroxyl radical oxidation in biological systems.

Briefly, this procedure is based on the ability of hydroxyl radicals to hydroxylate benzoate to give 2-, 3- and 4-hydroxylated benzoic acid products. Benzoic acid (1 mM) is incubated over time up to 81 h at room temperature in the dark in 10 mM phosphate buffer (pH 7.4) with 6 mM hydrogen peroxide, ferric chloride (30 μM) and the Fe chelator (30 μM). HPLC is the method of choice used to monitor and quantify the amount of 2-, 3- and 4-hydroxylated products formed over time in the reaction mixture, and can be verified against authentic benzoic acid and its hydroxylated products via their respective retention times and areas under curve. In addition, several controls are used: (i) a control without added Fe stock solution and Fe chelator; (ii) a control without added Fe chelator; (iii) EDTA as positive control; and (iv) deferiprone as negative control. The Fe-EDTA system is a hydroxyl radical generator and is known to promote hydroxylation of benzoic acid. Under the experimental conditions, the Fe chelate from the compounds of formula I (Apo7041, Apo7050, Apo7053 and Apo7077) do not promote the hydroxylation of benzoic acid.

Example 32

A. Neuroprotective Effect of Compounds of Formula I on Hydrogen Peroxide Induced Apoptosis in SH-SY5Y Neuroblastoma Cells

Hydrogen peroxide (H₂O₂) is a major ROS (reactive oxidative species), which causes oxidative stress, and can induce apoptosis in many different cell types. One of the CNS drug design strategies is to use compounds with antioxidant properties as a possible treatment of both acute and chronic neurodegenerative diseases (Kang et al. Bioorganic & Medicinal Chemistry Letters, 2004, 14, 2261-2264). This involves testing the compounds of this invention for their protective effect against oxidative stress-induced cell death in SH-SY5Y human neuroblastoma cells. SH-SY5Y human neuroblastoma cells were cultured in DMEM (ATCC)/F12 (Cellgro) with 10% FBS. The cells were plated at 30,000 cells/cm² and grown for 1 day in the regular culture media prior to compound addition. Cells were routinely treated with the test compound, at a pre-determined range of concentrations, in the presence or absence of 50 μM hydrogen peroxide in a basal medium containing no FBS for 16-22 h. Cell viability was then measured using the routine MTT method (Mosmann, T., Rapid Colorimetric Assay for Cellular Growth and Survival: Application to Proliferation and Cytotoxicity Assays”. J. Immunol. Meth. 1983, 65, 55-63).

For data analysis, cell viability relative to control not treated with either H₂O₂ or the test compound, was plotted against the compound concentration. The threshold protective concentration (TH) was defined as the highest concentration at which the compound did not display a significant protective effect (i.e. next higher concentration had a statistically significant protective effect) against hydrogen peroxide insult. Maximum effective concentration (EC₁₀₀) was a concentration at which the compound exhibited maximum protective effect. Cytotoxicity of the test compound was assessed in the absence of hydrogen peroxide. Cytotoxic concentration (CC1) was defined as the lowest compound concentration resulting in viability significantly below 80%. Cytotoxic concentration (CC2) was the lowest compound concentration resulting in viability significantly below 80% in H₂O₂-treated cells.

B. Evaluation of the Compounds in the Protection Against Endogenously Produced Aβ Toxicity

Amyloid plaques, are formed by the aggregation of small peptides, called amyloid β peptide (Aβ), that are produced when amyloid precursor protein (APP) is cleaved by the action of two enzymes, β-APP cleaving enzyme and γ-secretase. One approach to the treatment of Alzheimer's disease is, therefore, limiting the production of Aβ from its precursor by inhibiting one or both of these enzymes, while another approach is to inhibit the aggregration of Aβ via the use of metal chelators.

In this assay, human neuroblastoma cells (MC-65 cells) are genetically engineered to conditionally express amyloid β peptide (Aβ). The Aβ production is suppressed by tetracycline (TET+) presence in culture medium, and its production is activated when TET is withdrawn (TET−). The activation of Aβ production results in cell death “MC-65 suicide”.

Protective effect of compounds against edogenously produced amyloid beta (Aβ) was assessed in human neuroblastoma MC-65 cells. MC-65 cells have been stably transformed to conditionally express high levels of a partial amyloid precursor (AP) fusion protein (Bryce Sopher et al., Brain Res Mol Brain Res. 1994, 207-17.). This protein is further proteolitically processed in the cells to form a set of AP-derived Aβ peptides. AP conditional expression in these cells is under control of tetracycline-responsive promoter system and results in pronounced cytotoxicity. Activity of the promoter is tightly regulated by the presence of the antibiotic tetracycline (TET) in the culture medium. In the presence of TET (TET+), the promoter is in the basal state and no amyloid beta peptide is synthesized. In the absence of TET (TET−) the promoter is in induced state, resulting in the accumulation of Aβ peptides in the cells, degenerative changes in cell morphology and decreased survival.

Transfected human neuroblastoma cells (MC-65) were cultured in DMEM (ATCC) supplemented with non-essential amino acids and 10% FBS (VWR) in the presence of TET (1 μg/mL). For the experiment, the cells were plated at 35,000 cells/cm² and grown for 1 day in the regular culture media prior to compound addition. On the day of the assay, culture supernatant was removed from the wells and cells were thoroughly washed once with the compound incubation matrix containing no FBS and no TET. MC-65 cells were treated with a test compound at pre-determined range of concentrations in a basal medium containing no FBS and in the absence or presence of 1 μg/mL TET for approximately 48 h. Cell viability was then measured using the MTT method.

For data analysis, cell viabilities relative to the control not treated with a test compound and maintained in the presence of TET were plotted against the compound concentration. The threshold protective concentration (TH) was defined as the highest concentration at which the tested compound did not display a significant protective effect (i.e. next higher concentration had a statistically significant protective effect) in the group maintained in the absence of TET. Maximum effective concentration (EC₁₀₀) was a concentration at which the compound exhibited maximum protective effect. Cytotoxicity of the test compound was assessed in the cells maintained in the presence of TET. Cytotoxic concentration (CC1) was defined as the lowest compound concentration resulting in viability significantly below 80%. CC2 is the lowest compound concentration resulting in viability significantly below 80% in cells expressing AP (i.e. cultured without tetracycline).

Chemical Structures of Compounds

Apo# G¹ G² G³ G⁴ 6994 H CH₂CF₃ Me H 6995 Me CH₂CF₃ H H 6998 CH(CF₃)-D-ala-NHMe Me H H 7021 CH₂CF₃ Me CH₂NMe₂ H 7022 CH(OH)CF₃ Me CH₂NMe₂ H 7030 Et CH₂CF₃ H H 7032 CH(OH)CF₃ Me CH₂-L-ala-OH H 7033 CH(OH)CF₃ Me CH₂-L-ala-NHMe H 7035 CH(OH)CF₃ H CH₂NMe₂ H 7038 CH(OH)CF₃ Me Me Cl 7040 CH₂CF₃ Me Me Cl 7041 CH(NMe₂)CF₃ Me H H 7053 Me Me H CH(NMe₂)CF₃ 7054 Me Me H CH(piperidinyl)CF₃ 7055 Me Me H CH(imidazolyl)CF₃ 7056 Me Me H CH(NHMe)CF₃ 7057 CH(propargylamino)CF₃ Me H H 7058 CH(piperidinyl)CF₃ Me H H 7059 CH(NMe₂)CF₃ Me Me Cl 7060 CH(NMe₂)CF₃ Me H Cl 7061 CH(piperidinyl)CF₃ Me H Cl 7063 Me Me H CH(N-methylpiperazinyl)CF₃ 7065 CH₂NMe₂ CH₂CF₃ Me H 7066 CH₂CF₃ Me H Cl 7067 CH₂NMe₂ Me H H 7069 Me CH₂CHF₂ H H 7071 CH₂(piperidinyl) CH₂CF₃ Me H 7073 CH(N-methylpiperazinyl)CF₃ Me H H 7074 CH (cyclopropylamino)CF₃ Me H H 7075 CH (allylamino)CF₃ Me H H 7077 NMe₂ Me CH₂CF₃ H 7080 CH₂CHF₂ Me H H 7083 CH2NMe₂ CH₂CHF₂ Me H 7316 CH(pyrid-2- Me H H ylpiperazinyl)CF₂H 7319 CH(piperidinyl)CF₂H Me H H 7323 CH₂(morpholinyl) CH₂CF₃ H H 7333 CH(morpholinyl)CF₃ Me Me H 7334 CH(N-benzylpiperazinyl)CF₃ Me Me H 7335 CH(N-phenylpiperazinyl)CF₃ Me Me H 7336 CH(pyrid-2-ylpiperazinyl)CF₃ Me Me H 7433 Me H H CH(morpholinyl)CF₃ 7434 CH₂(morpholinyl) CH₂CF₃ Me H 7435 Me Me H CH(morpholinyl)CF₃ 7448 CH(morpholinyl)CF₃ Me H H Test Results of Neuroprotective Effect of Compounds of Formula I on Hydrogen Peroxide Induced Apoptosis in SH-SY5Y Neuroblastoma Cells.

TH EC₁₀₀ CC1 CC2 Apo# (μM) (μM) (μM) (μM) 6994 40 160 160 640 6995 20 160 320 320 6998 10 80 20 100 7021 2.5 640 80 >640 7022 5 160 40 320 7030 10 320 640 >640 7032 160 640 10 >640 7035 20 640 40 >640 7038 20 320 40 >640 7040 10 640 160 >640 7041 10 80 160 320 7053 10 40 2.2 >640 7054 2.5 640 5 >640 7055 2.5 40 10 >640 7057 3 20 5 80 7058 5 640 20 >640 7059 10 320 40 640 7060 20 320 80 >640 7061 10 640 10 10 7066 10 40 160 160 7067 10 40 160 >640 7069 40 160 80 >640 7071 3 20 20 80 7073 5 640 40 >640 7074 3 640 20 >640 7075 3 640 20 >640 7080 10 320 40 >640 7033 160 640 40 >640 7063 5 640 320 >640 7065 5 40 40 >640 7316 5 40 320 320 7319 5 80 320 320 7323 10 40 160 320 7333 5 20 320 320 7334 5 160 40 320 7335 5 10 80 80 7336 5 20 80 80 7433 5 320 320 320 7434 5 320 320 320 7435 5 160 80 320 7448 10 160 80 320 MC65 Assay Testing Results in the Protection Against Endogenously Produced AR Toxicity

TH EC₁₀₀ CC1 CC2 Apo# (μM) (μM) (μM) (μM) 6994 1 10 >80 >80 6995 0.1 20 80 80 7021 0.1 10 10 20 7022 0.1 20 10 40 7030 1 20 40 40 7032 0.1 10 80 40 7035 0.1 10 40 20 7040 1 40 40 80 7041 0.1 10 10 80 7053 0.1 10 40 20 7054 0.1 1 20 20 7055 1 20 40 40 7056 0.1 10 80 80 7057 1 10 20 20 7058 1 10 10 80 7059 1 10 10 40 7060 1 10 40 20 7061 1 10 40 20 7066 0.1 10 80 80 7067 0.1 10 80 80 7069 0.1 40 80 80 7071 1 10 40 20 7073 0.1 10 40 20 7074 0.1 10 10 20 7075 0.1 10 10 20 7077 1 10 80 80 7080 0.1 10 40 40 7083 0.1 10 40 40 7316 1 10 10 20 7319 1 10 40 40 7323 1 20 80 80 7333 1 10 20 40 7334 1 10 10 20 7335 1 10 20 20 7336 1 10 10 20 7433 1 10 40 40 7434 1 20 40 40 7435 1 10 40 40 7448 1 20 40 40

Example 33

Influence of MPP⁺ (5 mM) on SV-NRA Cell Viability and the Neuroprotective Actions of Compounds of Formula I (Apo6995, Apo7060, 7021) on MPP⁺ Treated SV-NRA Cells

SV-NRAs cells were plated in a 96-well plate at a density of 10,000 cells/well in 100 μL of DME (dimethoxyethane), high glucose 1× liquid (Sigma) supplemented with 10% heat-inactivated FBS and 1× antibiotic/antimycotic solution (Sigma). On the next day, the cells were washed with EMEM media (Eagle's minimal essential media; phenol red, serum and glutamine free) and treated for 24 h with 5 mM MPP⁺ (1-methyl-4-phenylpyridinium) in EMEM media in the presence or absence of a tested iron chelating compound. All compounds were tested at the following concentrations: 10 μM, 20 μM, and 40 μM. After 24 h of incubation, cell viability was determined with MTT ((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole) assay which measures mitochondrial activity (Carmichael et al. Cancer Research 1987, 47, 936-942). MTT solution (10 μL, 5 mg/mL) was added to the wells and incubated for 2 h. Formazan product was solubilized with 100 μL of 10% SDS (sodium dodecyl sulphate) in 0.01M HCl. Optical density was determined at 570 nm using Multiscan Ascent plate reader (Labsystems) and data collected were corrected for background signal measured at 650 nm. All data are expressed as % of control.

MPP+ treatment resulted in about 40%-50% decrease in cell viability compared to vehicle-treated control. Co-treatment with iron chelators protected the cells from MPP⁺ toxicity. Treatment with 20 μM deferiprone, an iron chelator drug resulted in about 20% increase in cell viability (p<0.05). Treatment with iron chelators Apo7060, Apo6995 and Apo7021 at concentrations of 10, 20, and 40 μM also increased cell viability by 20-30% (p<0.05) compared to MPP+ only treated cells. Representative results are shown in FIGS. 10, 11, 12, and 13.

Example 34 Preparation of 3-hydroxy-2-methyl-5-(2,2,2-trifluoro-1-morpholinoethyl) pyridin-4(1H)-one (Apo7433)

Morpholine (14.1 g, 161.80 mmol) was added to a solution of 5-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-2-methylpyridin-4(1H)-one hydrochloride (4.5 g, 16.18 mmol) in ethanol with cooling in an ice-water bath. The reaction mixture was stirred for 10 min, and then was concentrated in vacuo by rotary evaporation. The resulting crude product was mixed with water, and the resulting solid was collected via suction filtration. The solid was successively rinsed with water and ether to give 3-hydroxy-2-methyl-5-(2,2,2-trifluoro-1-morpholinoethyl) pyridin-4(1H)-one (3.85 g) as a white solid. Yield=81%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 7.57 (s, 1H), 4.81 (q, J=9.8 Hz, 1H), 3.65 (br t, J=4.4 Hz, 4H), 2.63-2.70 (m, 2H), 2.54-2.61 (m, 2H), 2.34 (s, 3H); LC-MS-ESI (m/z): 293 [M+1]⁺.

Example 35 Preparation of 3-hydroxy-1,2-dimethyl-5-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one (Apo7435)

3-Hydroxy-1,2-dimethyl-5-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (1.0 g, 4.2 mmol) was mixed with thionyl chloride (1 mL) in acetonitrile (10 mL) at 60° C. and stirred for 30 min, following which, the reaction mixture was concentrated under reduced pressure by rotary evaporation. The residue was dissolved in acetonitrile (10 mL) and mixed with morpholine (3.67 g, 42 mmol). The resulting mixture was stirred at 50° C. for 30 min and then concentrated by rotary evaporation. The resulting residue was diluted with water and the pH of the mixture was adjusted to 6-7 with a 6N HCl solution. The resulting solid was collected via suction filtration, then rinsed with water and ether to give 3-hydroxy-1,2-dimethyl-5-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one (955 mg) as a white solid. Yield=74%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 7.73 (s, 1H), 4.82 (q, J=9.3 Hz, 1H), 3.80 (s, 3H), 3.65 (br t, J=4.8 Hz, 4H), 2.63-2.70 (m, 2H), 2.54-2.61 (m, 2H), 2.34 (s, 3H); LC-MS (m/z): 307 [M+1]⁺.

Example 36 Preparation of 3-hydroxy-6-methyl-2-(morpholinomethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo7434)

2-((Dimethylamino)methyl)-3-hydroxy-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (4.3 g, 16.27 mmol) was mixed with morpholine (14.2 g, 162.0 mmol) in ethanol and a 6N NaOH solution (2.6 mL, 15.60 mmol). The reaction mixture was refluxed for 65 hours, and then concentrated to dryness by rotary evaporation. The residue was diluted with water, then the pH of the mixture was adjusted to 3-4. The resulting solid was collected via suction filtration, rinsed with water and ether to give 3-hydroxy-6-methyl-2-(morpholinomethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (1.95 g). Yield=39%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 6.37 (s, 1H), 5.71 (br, 1H), 4.48 (br, 1H), 3.98 (br, 1H), 3.50-3.70 (m, 5H), 2.40-2.55 (m, 7H); LC-MS-ESI (m/z): 307 [M+1]⁺.

Example 37 Preparation of 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(4-phenyl piperazin-1-yl)ethyl)pyridin-4(1H)-one (Apo7324)

A. Preparation of 5-(1-chloro-2,2,2-trifluoroethyl)-2-ethyl-3-hydroxypyridin-4(1H)-one hydrochloride

A solution of 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (13 g, 54.8 mmol) and thionyl chloride (4.4 mL, 60.3 mmol) in CH₃CN (50 mL) was heated at 50° C. for 3 h, following which an additional 1.6 mL of thionyl chloride (22.4 mmol) was added and the reaction mixture was heated for another 2 h. The heating bath was then removed and the mixture was cooled down to RT, then at 0° C. for 10 min. The resulting precipitate was collected by suction filtration and dried to yield 5-(1-chloro-2,2,2-trifluoroethyl)-2-ethyl-3-hydroxypyridin-4(1H)-one hydrochloride as an off-white solid (12.9 g, 81%). ¹H NMR (DMSO-D₆, 400 MHz) δ (ppm): 11.9 (s, 1H), 7.70 (d, J=6.2 Hz, 1H), 6.05 (q, J=7.8 Hz, 1H), 2.60 (q, J=7.7 Hz, 2H) and 1.15 (t, J=7.7 Hz, 3H); MS-ESI m/z: 256 [M+1]⁺.

B. Preparation of 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(4-phenylpiperazin-1-yl)ethyl)pyridin-4(1H)-one (Apo7324)

To a solution of 1-phenylpiperazine (2.63 mL, 17.2 mmol) in CH₃CN (36 mL) was added 5-(1-chloro-2,2,2-trifluoroethyl)-2-ethyl-3-hydroxypyridin-4(1H)-one hydrochloride (1.0 g, 3.44 mmol) portionwise at 0° C. After 2.5 h, volatile materials were removed in vacuo and the resulting residue was stirred with 30 mL water for 30 min. The resulting precipitate was collected by suction filtration, washed with water (30 mL×2), hexanes (30 mL×2), Et₂O (30 mL×2) and dried in a vacuum oven at a preset temperature of 40° C. overnight to yield 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(4-phenylpiperazin-1-yl)ethyl)pyridin-4(1H)-one as a white solid (1.0 g, 78%). ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 7.62 (s, 1H), 7.22 (dd, J=8.0, 7.6 Hz, 2H), 6.92 (d, J=8.0 Hz, 2H), 6.82 (t, J=7.6 Hz, 1H), 4.90 (q, J=9.6 Hz, 1H), 3.14 (t, J=4.9 Hz, 4H), 2.81-2.85 (m, 2H), 2.73-2.79 (m, 4H) and 1.27 (t, J=7.6 Hz, 3H); MS-ESI m/z: 382 [M+1]⁺.

Example 38 Preparation of 5-(1-(4-benzyl piperazin-1-yl)-2,2,2-trifluoroethyl)-2-ethyl-3-hydroxypyridin-4(1H)-one (Apo7325)

To a solution of 1-benzylpiperazine (3.0 mL, 17.2 mmol) in CH₃CN (24 mL) was added 5-(1-chloro-2,2,2-trifluoroethyl)-2-ethyl-3-hydroxypyridin-4(1H)-one hydrochloride (1.0 g, 3.44 mmol) portionwise at 0° C. After 2 h, volatile materials were removed in vacuo. The resulting residue was partitioned between water (50 mL) and CH₂Cl₂ (50 mL) and the aqueous layer was extracted with CH₂Cl₂ (50 mL×2). The combined organic layers was evaporated to yield a white solid, which was washed with water (50 mL×2), stirred with water/methanol (100 mL, 9:1 v/v) for 30 min and then Et₂O/hexanes (100 mL, 9:1 v/v) for overnight. The precipitate was collected via suction filtration and dried in a vacuum oven at a preset temperature of 40° C. for overnight to yield 5-(1-(4-benzylpiperazin-1-yl)-2,2,2-trifluoroethyl)-2-ethyl-3-hydroxypyridin-4(1H)-one as a white solid (0.7 g, 52%). ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 7.46 (s, 1H), 7.25-7.27 (m, 5H), 4.90 (q, J=9.6 Hz, 1H), 3.47 (s, 2H), 2.62-2.75 (m, 6H), 2.38-2.48 (m, 4H) and 1.24 (t, J=7.5 Hz, 3H); MS-ESI m/z: 396 [M+1]⁺.

Example 39 Preparation of 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)pyridin-4(1H)-one (Apo7326)

To a solution of 1-(2-pyridyl)piperazine (1.3 mL, 8.59 mmol) in CH₃CN (18 mL) was added 5-(1-chloro-2,2,2-trifluoroethyl)-2-ethyl-3-hydroxypyridin-4(1H)-one hydrochloride (0.5 g, 1.72 mmol) portionwise at 0° C. After 2 h, volatile materials were removed in vacuo and the resulting residue was stirred with 30 mL water for 30 min. The resulting precipitate was collected by suction filtration, washed with water (30 mL×2), hexanes (30 mL×2), Et₂O (30 mL×2) and dried in a vacuum oven at a preset temperature of 40° C. for overnight to yield 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)pyridin-4(1H)-one as a white solid (0.47 g, 71%). ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 8.03-8.04 (m, 1H), 7.62 (s, 1H), 7.53 (dd, J=7.2, 8.5 Hz, 1H), 6.78 (d, J=8.5 Hz, 1H), 6.63-6.66 (m, 1H), 4.90 (q, J=9.6 Hz, 1H), 3.46-3.47 (m, 4H), 2.70-2.79 (m, 6H) and 1.27 (t, J=7.6 Hz, 3H); MS-ESI m/z: 383 [M+1]⁺.

Example 40 Preparation of 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(1H-1,2,4-triazol-1-yl)ethyl)pyridin-4(1H)-one (Apo7331)

To a solution of 1,2,4-triazole sodium (6.8 g, 75 mmol, technical grade, 90%) in water (45 mL) was added a suspension of 5-(1-chloro-2,2,2-trifluoroethyl)-2-ethyl-3-hydroxypyridin-4(1H)-one hydrochloride (4.4 g, 15 mmol) in CH₃CN (90 mL) portionwise at 0° C. The resulting mixture was slowly warmed up to RT and stirred overnight. After 18 h, volatile materials were removed in vacuo and the resulting residue was partitioned between water (100 mL) and EtOAc (200 mL). The organic layer was washed with water (100 mL×3), brine (100 mL×3), dried over MgSO₄, filtered and concentrated to yield a slurry, which was extracted extensively with Et₂O (50 mL×6). The combined Et₂O extracts were concentrated to yield a slightly yellow solid, which was recrystallized further from EtOAc/hexanes. The precipitated material was collected via suction filtration and dried in a vacuum oven at 40° C. for overnight to yield 2-ethyl-3-hydroxy-5-(2,2,2-trifluoro-1-(1H-1,2,4-triazol-1-yl)ethyl)pyridin-4(1H)-one as a white solid (0.9 g, 21%). ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 8.81 (s, 1H), 8.19 (s, 1H), 8.07 (s, 1H), 6.89 (q, J=7.8 Hz, 1H), 2.74 (q, J=7.5 Hz, 2H) and 1.25 (t, J=7.5 Hz, 3H); MS-ESI m/z: 289 [M+1]⁺.

Example 41 Preparation of 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one (Apo7333)

A. Preparation of 2-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,6-dimethylpyridin-4(1H)-one hydrochloride

To a suspension of 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H)-one (32.0 g, 134.9 mmol) in CH₃CN (130 mL) was added thionyl chloride (17.2 mL, 236.8 mmol) at RT, and the mixture was then stirred for 4 h. The resulting solid was collected through suction filtration, washed with a mixture of MTBE (methyl tert-butyl ether)/Et₂O, and then dried under vacuum at a preset temperature of 41° C. for overnight. The title compound was obtained as a white solid (32.9 g).

B. Preparation of 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one (Apo7333)

To a solution of morpholine (1.26 mL, 14.4 mmol) in 20 mL of EtOH was added 2-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,6-dimethylpyridin-4(1H)-one hydrochloride (1.0 g, 3.42 mmol) at RT, and the mixture was then stirred for three days. The resulting solid was collected via suction filtration, was thoroughly washed with water and Et₂O, and then dried under vacuum at a preset temperature of 40° C. for 4 h to afford 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one (613 mg). Yield=58%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 6.40 (s, 1H), 5.08 (q, J=8.5 Hz, 1H), 4.02 (s, 3H), 3.71-3.73 (m, 4H), 2.62-2.78 (m, 2H), 2.40-2.49 (m, 2H) and 2.40 (s, 3H); MS-ESI m/z: 307 [M+1]⁺.

Example 42 Preparation of 2-(1-(4-benzylpiperazin-1-yl)-2,2,2-trifluoroethyl)-3-hydroxy-1,6-dimethylpyridin-4(1H)-one (Apo7334)

To a solution of 1-benzylpiperazine (3.98 mL, 22.9 mmol) in 30 mL of EtOH was added 2-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,6-dimethylpyridin-4(1H)-one hydrochloride (2.0 g, 6.85 mmol) at RT, and the mixture was then stirred for overnight. The resulting solid was collected via suction filtration, washed with water and Et₂O, and then dried under vacuum at a preset temperature of 40° C. for 4 h to afford 2-(1-(4-benzylpiperazin-1-yl)-2,2,2-trifluoroethyl)-3-hydroxy-1,6-dimethylpyridin-4(1H)-one (1.7 g). Yield=62%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 7.24-7.31 (m, 5H), 6.39 (s, 1H), 5.07 (q, J=8.5 Hz, 1H), 4.00 (s, 3H), 3.52 (s, 2H), 2.48-2.91 (m, 8H) and 2.39 (s, 3H); MS-ESI m/z: 396 [M+1]⁺.

Example 43 Preparation of 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-(4-phenylpiperazin-1-yl)ethyl)pyridin-4(1H)-one (Apo7335)

To a solution of 1-phenylpiperazine (2.6 mL, 17.0 mmol) in 20 mL of EtOH was added 2-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,6-dimethylpyridin-4(1H)-one hydrochloride (1.0 g, 3.4 mmol) at RT, and the mixture was then stirred for overnight. The resulting solid was collected via suction filtration, washed with water and Et₂O, and then dried under vacuum at a preset temperature of 40° C. for 5 h to afford 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-(4-phenylpiperazin-1-yl)ethyl)pyridin-4(1H)-one (1.0 g). Yield=78%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 7.22 (t, J=7.9 Hz, 2H), 6.96 (d, J=8.2 Hz, 2H), 6.84 (t, J=7.3 Hz, 1H), 6.42 (s, 1H), 5.14 (q, J=8.5 Hz, 1H), 4.04 (s, 3H), 3.20-3.25 (m, 4H), 2.80-2.90 (m, 2H), 2.60-2.70 (m, 2H) and 2.42 (s, 3H); MS-ESI m/z: 382 [M+1]⁺.

Example 44 Preparation of 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)pyridin-4(1H)-one (Apo7336)

To a solution of 1-(2-pyridyl)piperazine (2.1 mL, 13.7 mmol) in 20 mL of EtOH was added 2-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1,6-dimethylpyridin-4(1H)-one hydrochloride (1.0 g, 3.4 mmol) at RT, and the mixture was then stirred for overnight. The resulting solid was collected via suction filtration, washed with water and Et₂O, and then dried under vacuum at a preset temperature of 40° C. for overnight to afford 3-hydroxy-1,6-dimethyl-2-(2,2,2-trifluoro-1-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)pyridin-4(1H)-one (943 mg) as white solid. Yield=72%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 8.08 (d, J=4.6 Hz, 1H), 7.56 (t, J=7.7 Hz, 1H), 6.83 (d, J=8.7 Hz, 1H), 6.69 (t, J=5.9 Hz, 1H), 6.42 (s, 1H), 5.13 (q, J=8.4 Hz, 1H), 4.05 (s, 3H), 3.53-3.57 (m, 4H), 2.70-2.80 (m, 2H), 2.55-2.65 (m, 2H) and 2.42 (s, 3H); MS-ESI m/z: 383 [M+1].

Example 45 Preparation of 3-hydroxy-2-(morpholinomethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo7323) A. Preparation of 3-hydroxy-2-(hydroxymethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one

A mixture of 3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (25.0 g. 130 mmol), 37% aqueous formaldehyde solution (193 mL, 2.59 mol) and 10N sodium hydroxide solution (19.4 mL, 194 mmol) was stirred at 45° C. oil bath temperature for 18 h, and then an additional 37% aqueous formaldehyde solution (19 mL, 259 mmol) was added. The reaction mixture was then stirred at 50° C. for another 3 h, following which, a 6N HCl solution (19.4 mL, 116.5 mmol) was added. The clear reaction mixture was concentrated in vacuo by rotary evaporation to give a thick slurry. De-ionized water (200 mL) was added and the pH of the mixture was adjusted to about 5 with a 6N HCl solution. The mixture was stirred at RT for 1.5 h, during which time a solid precipitated. The solid was collected via suction filtration, and was further rinsed washed with de-ionized water (40 mL). The solid was then purified by column chromatography on silica gel with a gradient mixture of 0-20% methanol in dichloromethane as eluant. The product obtained was mixed with methanol (50 mL), stirred at RT for 15 min and filtered to give 3-hydroxy-2-(hydroxymethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (23.0 g) as white solid. Yield=80%; ¹H NMR (DMSO-d₆+D₂O, 400 MHz) δ ppm: 7.70 (d, J=8.08 Hz, 1H), 6.36 (d, J=7.07 Hz, 1H), 4.96-5.15 (m, 2H), 4.68 (s, 2H); MS-ESI m/z: 224 [M+1]⁺.

B. Preparation of 2-(chloromethyl)-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one hydrochloride

To a solution of 3-hydroxy-2-(hydroxymethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (2.0 g, 9.0 mmol) in CH₂Cl₂ (10 mL) and DMF (0.026 mL, 0.035 mmol) cooled in an ice-water bath (bath T=8-10° C.) was added oxalyl chloride (1.18 mL, 13.5 mmol) dropwise over 10 min. The mixture was allowed to warm to RT and stirred at RT for 1.5 h. DMF (0.052 mL, 0.72 mmol) was added and then stirred at RT for 16 h. The reaction mixture was filtered and the isolated yellow solid was washed with CH₂Cl₂ (10 mL×8) to give 2-(chloromethyl)-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one hydrochloride quantitatively.

C. Preparation of 3-hydroxy-2-(morpholinomethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (Apo7323)

A solution of 2-(chloromethyl)-3-hydroxy-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one hydrochloride (1.25 g, 4.5 mmol) in acetonitrile (25 mL) was added dropwise over 5 min to an ice cooled (bath T=8-10° C.) solution of morpholine (2.35 mL, 26.9 mmol) solution in CH₃CN (5 mL). The mixture was allowed to warm to RT and stirred for 40 min. The resulting solid was collected via suction filtration, then partitioned between de-ionized water (25 mL) and CH₂Cl₂ (50 mL). The organic fraction was collected, and the aqueous part was further extracted with CH₂Cl₂ (25 mL×2). The combined CH₂Cl₂ parts were washed with de-ionized water (10 mL×2), then dried over anhydrous sodium sulfate and filtered. Solvent was removed under reduced pressure to give 3-hydroxy-2-(morpholinomethyl)-1-(2,2,2-trifluoroethyl)pyridin-4(1H)-one (0.7 g) as a white solid. Yield=53%; ¹H NMR (CD₃OD, 400 MHz) δ ppm: 7.68 (d, J=7.1 Hz, 1H), 6.42 (d, J=7.1 Hz, 1H), 5.13-5.21 (m, 2H), 3.75 (s, 2H), 3.65-3.67 (m, 4H), 2.45-2.50 (m, 4H); MS-ESI m/z: 293 [M+1]⁺.

Example 46 Preparation of 2-(2,2-difluoro-1-morpholinoethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (Apo7314)

A. Preparation of 2-(1-chloro-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride

To a mixture of 2-(2,2-difluoro-1-hydroxyethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (950 mg, 4.63 mmol) in acetonitrile (5 mL) heated in an oil bath at 60° C. was added thionyl chloride (2.75 g, 23.15 mmol). After stirring for 20 min, the reaction mixture was concentrated in vacuo and the residue was triturated with ether at room temperature overnight. The resulting off-white solid was collected via suction filtration, then washed with MTBE to give 2-(1-chloro-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride (1.18 g, 98% yield).

B. Preparation of 2-(2,2-difluoro-1-morpholinoethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (Apo7314)

A mixture of 2-(1-chloro-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride (100 mg, 0.384 mmol) and morpholine (300 mg, 3.44 mmol) in dichloromethane (5 mL) was stirred at room temperature for overnight. The reaction mixture was diluted with dichloromethane, and the mixture then washed with water and brine, dried with MgSO₄, and filtered. The filtrate was concentrated in vacuo, and the residue was triturated with ether to give 2-(2,2-difluoro-1-morpholinoethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (25 mg) as an off-white solid. Yield=24%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 6.91-7.60 (m, 2H), 6.33 (d, J=5.1 Hz, 1H), 4.13-4.37 (m, 1H), 3.90 (br. s, 3H), 3.54-3.68 (m, 4H), 2.84-2.95 (m, 2H), 2.62-2.81 (m, 2H); MS-ESI (m/z): 275 [M+1]⁺.

Example 47 Preparation of 2-(2,2-difluoro-1-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)-3-hydroxy-1-methyl pyridin-4(1H)-one (Apo7316)

A mixture of 2-(1-chloro-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride (100 mg, 0.384 mmol) and 1-(2-pyridinyl)-piperazine (470 mg, 2.88 mmol) in dichloromethane (5 mL) was stirred at RT for overnight. The reaction mixture was diluted with dichloromethane, then washed with water and brine, dried with MgSO₄, and filtered. The filtrate was concentrated in vacuo and the residue triturated with ether to give 2-(2,2-difluoro-1-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (35 mg) as an off-white solid. Yield=26%; ¹H NMR (CD₃OD, 400 MHz): δ (ppm) 8.06 (d, J=4.0 Hz, 1H), 7.53 (t, J=7.1 Hz, 2H), 6.80-7.40 (br. m, 1H), 6.77 (d, J=8.1 Hz, 1H), 6.66 (t, J=5.6 Hz, 1H), 6.36 (d, J=6.1 Hz, 1H), 4.20-4.50 (m, 1H), 3.93 (s, 3H), 3.36-3.54 (m, 4H), 2.73-3.11 (m, 4H); MS-ESI (m/z): 351 [M+1]⁺.

Example 48 Preparation of 2-(2,2-difluoro-1-(4-phenyl piperazin-1-yl)ethyl)-3-hydroxy-1-methyl pyridin-4(1H)-one (Apo7317)

A mixture of 2-(1-chloro-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride (100 mg, 0.384 mmol) and N-phenyl-piperazine (500 mg, 3.08 mmol) in dichloromethane (5 mL) was stirred at RT for overnight. The reaction mixture was diluted with dichloromethane, and then washed with water and brine, dried with MgSO₄, filtered. The filtrate was concentrated in vacuo and the residue was triturated with ether to give 2-(2,2-difluoro-1-(4-phenylpiperazin-1-yl)ethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (42 mg) as an off-white solid. Yield=31%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 7.65 (d, J=6.1 Hz, 1H), 7.21 (t, J=7.6 Hz, 2H), 6.67-7.09 (m, 4H), 6.40 (d, J=7.1 Hz, 1H), 4.27-4.46 (m, 1H), 3.93 (s, 3H), 2.80-3.22 (m, 8H); MS-ESI (m/z): 350 [M+1]⁺.

Example 49 Preparation of 2-(1-(4-benzyl piperazin-1-yl)-2,2-difluoroethyl)-3-hydroxy-1-methyl pyridin-4(1H)-one (Apo7318)

A mixture of 2-(1-chloro-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride (100 mg, 0.384 mmol) and N-benzyl-piperazine (500 mg, 3.08 mmol) in dichloromethane (5 mL) was stirred at room temperature for overnight. The reaction mixture was diluted with dichloromethane, then washed with water and brine, dried with MgSO₄, and filtered. The filtrate was concentrated in vacuo and the residue was triturated with ether to give 2-(1-(4-benzylpiperazin-1-yl)-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (28 mg) as an off-white solid. Yield=20%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 6.76-7.49 (m, 7H), 6.07-6.39 (m, 1H), 4.03-4.27 (m, 1H), 3.80 (br. s, 3H), 3.38-3.57 (m, 2H), 2.84-3.06 (m, 2H), 2.63-2.82 (m, 2H), 2.29-2.56 (m, 4H); MS-ESI (m/z): 364 [M+1]⁺.

Example 50 Preparation of 2-(2,2-difluoro-1-(4-methylpiperazin-1-yl)ethyl)-3-hydroxy-1-methyl pyridin-4(1H)-one (Apo7315)

A mixture of 2-(1-chloro-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride (100 mg, 0.384 mmol) and N-methylpiperazine (350 mg, 3.49 mmol) in dichloromethane (5 mL) was stirred at RT for overnight. The reaction mixture was diluted with dichloromethane and washed with water and brine, dried with MgSO₄, and filtered. The filtrate was concentrated in vacuo and the residue triturated with ether to give 2-(2,2-difluoro-1-(4-methylpiperazin-1-yl)ethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (30 mg) as an off-white solid. Yield=27%.%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 6.90-7.59 (m, 2H), 6.32 (d, J=6.1 Hz, 1H), 4.08-4.33 (m, 1H), 3.88 (s, 3H), 2.92-3.09 (m, 2H), 2.69-2.88 (m, 2H), 2.37-2.61 (m, 4H), 2.28 (s, 3H); MS-ESI (m/z): 288 [M+1]⁺.

Example 51 Preparation of 2-(2,2-difluoro-1-(piperidin-1-yl)ethyl)-3-hydroxy-1-methyl pyridin-4(1H)-one (Apo7319)

A mixture of 2-(1-chloro-2,2-difluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one hydrochloride (100 mg, 0.384 mmol) and piperidine (375 mg, 4.40 mmol) in dichloromethane (5 mL) was stirred at RT for overnight. The reaction mixture was diluted with dichloromethane, then washed with water and brine, dried with MgSO₄, and filtered. The filtrate was concentrated in vacuo and the residue was triturated with ether to give 2-(2,2-difluoro-1-(piperidin-1-yl)ethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (29 mg) as an off-white solid. Yield=28%; ¹H NMR (CD₃OD, 400 MHz) δ (ppm): 6.80-7.70 (m, 2H), 6.32 (d, J=5.1 Hz, 1H), 3.99-4.20 (m, 1H), 3.88 (s, 3H), 2.84-3.02 (m, 2H), 2.58-2.77 (m, 2H), 1.34-1.59 (m, 6H); MS-ESI (m/z): 273 [M+1]⁺.

Example 52 Preparation of 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-morpholinoethyl)pyridin-4(1H)-one (Apo7448)

To a suspension of 3-hydroxy-1-methyl-2-(2,2,2-trifluoro-1-hydroxyethyl)pyridin-4(1H-one (10.0 g, 45 mmol) in acetonitrile (80 mL) cooled in an ice-water bath was added thionyl chloride (3.9 mL, 54 mmol) dropwise. After stirring for 2 hours, diethyl ether (100 mL) was added and the resulting precipitate, 2-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one, was isolated by filtration as a white solid.

2-(1-chloro-2,2,2-trifluoroethyl)-3-hydroxy-1-methylpyridin-4(1H)-one (9.15 g, 38 mmol) was added in portions to a solution of morpholine (16 mL, 179 mmol) in ethanol (150 mL) cooled in an ice-water bath. The reaction mixture was stirred for 3 hours, following which the resulting solid was filtered, washed with water and Et₂O, and dried under vacuum at 40° C. overnight to afford the title compound Apo7448 (5.18 g). Yield=47%; ¹H NMR (400 MHz, CD₃OD) δ (ppm): 7.6 (br. s, 1H), 6.40 (d, J=7.16 Hz, 1H), 5.03 (br. s, 1H), 4.08 (s, 3H), 3.71-3.86 (m, 4H), 2.45-2.87 (m, 4H); MS-ESI m/z 293 [M+1]⁺.

Example 53

Chelation Properties of Apo7323, Apo7067, Apo7435 and Apo7056

A. Apo7323.

The pKa values of Apo7323 were determined by spectrophotometric titration using an Agilent 8453 UV-visible spectroscopy system (see Example 26). The titration data were fitted with pHAB and the results are shown below.

The log β values of the Fe-Apo7323 system were determined by spectrophotometric titration using an Agilent 8453 UV-visible spectroscopy system (see Example 29B). The sample solution was a mixture of Fe³⁺ (2×10⁻⁴ M) and Apo7323 (1×10⁻³ M) in 0.1 N NaCl aqueous solvent. The titration data in a pH range of 3.408 to 0.655 were fitted with pHAB using the model shown in FIG. 1 to obtain Log β₁₁₁, Log β₁₂₂, and Log β₁₃₃.

The model symbol value Fe³⁺ + LH ⇄ (FeLH)³⁺ Log β₁₁₁ 18.4 (FeLH)³⁺ + LH ⇄ (FeL₂H₂)³⁺ Log β₁₂₂ 34.9 (FeL₃H₂)²⁺ + H⁺ ⇄ (FeL₃H₃)³⁺ Log β₁₃₃ 50.1

The sample solution was a mixture of Fe³⁺ (6×10⁻³M) and Apo7323 (1.8×10⁻²M) in 0.1 N NaCl aqueous solvent. The titration started at pH 1.72 and ended at pH 11.5 using 3 M NaOH as the titrant. The titration data in a pH range of 3 to 10 were fitted with Hyperquad2000 software using the model:

where 133 is the species (FeL₃H₃)³⁺, 132 is the species is (FeL₃H₂)²⁺, 131 is the species (FeL₃H)⁺, and 130 is the species FeL₃.

Log β₁₃₂, Log β₁₃₁, and Log β₁₃₀ were then calculated using the following three equations: Log β₁₃₂=Log β₁₃₃−pKa3(C)=50.1−3.9=46.2  1 Log β₁₃₁=Log β₁₃₂−pKa2(C)=46.2−4.6=41.6  2 Log β₁₃₀=Log β₁₃₁−pKa1(C)=41.6−5.9=35.7  3

After obtaining three pKa values for Apo7323 (ligand), three pKa values for the Fe-Apo7323 complex, and the log β values for Fe-Apo7323 as shown in the following table, a speciation plot (FIG. 14) was constructed using the HySS software program. pFe was also calculated using the HySS software.

Logβ₁₁₁ 18.4 K₁₁₁ 18.4 Logβ₁₂₂ 34.9 K₁₂₂ 16.5 Logβ₁₃₃ 50.1 K₁₃₃ 15.1 Logβ₁₃₂ 46.2 pKa3(C) 3.9 Logβ₁₃₁ 41.6 pKa2(C) 4.6 Logβ₁₃₀ 35.7 pKa1(C) 5.9 Logβ₀₁₁ 9.2 pKa1(L) 9.2 Logβ₀₁₂ 13.4 pKa2(L) 4.2 Logβ₀₁₃ 14.2 pKa3(L) 0.8

The speciation plot in FIG. 14 shows that 96.9% of the ferric chelate is Fe(Apo7323)₃ in neutral form.

Species % at pH 7.4 # of charges on chelate FeL₂H₂ 0.0 3 positive charge FeL₃H₃ 0.0 3 positive charge FeL₃H₂ 0.0 2 positive charge FeL₃H 3.1 1 positive charge FeL₃ 96.9 Neutral ferric chelate B. Apo7067

Proceeding in the same manner as described for Apo7323, the pKa values of Apo7067 and the Fe-Apo7067 system were determined, and the speciation of Fe-Apo7067 was constructed.

Logβ₁₁₁ 20.0 K₁₁₁ 20.0 Logβ₁₂₂ 38.7 K₁₂₂ 18.7 Logβ₁₃₃ 55.7 K₁₃₃ 17.0 Logβ₁₃₂ 49.6 pKa3(C) 6.1 Logβ₁₃₁ 42.6 pKa2(C) 7.0 Logβ₁₃₀ 34.5 pKa1(C) 8.1 Logβ₀₁₁ 9.6 pKa1(L) 9.6 Logβ₀₁₂ 15.7 pKa2(L) 6.1 Logβ₀₁₃ 16.5 pKa3(L) 0.8

The speciation plot in FIG. 15 shows that, with a pK_(a) of 6.1, the speciation analysis of Fe-Apo7067 system at about pH 7.4, the majority of the ferric chelate (87.6%) is in charged form.

Species % at pH 7.4 # of charges on chelate FeL₃H₃ 1.2 3 positive charge FeL₃H₂ 24.6 2 positive charge FeL₃H 61.8 1 positive charge FeL₃ 12.3 Neutral ferric chelate C. Apo7435

Proceeding in the same manner as described for Apo7323, the pKa values of Apo7435 and the Fe-Apo7435 system were determined, and the speciation of Fe-Apo7435 was constructed.

Logβ₁₁₁ 15.9 K₁₁₁ 15.9 Logβ₁₂₂ 30.4 K₁₂₂ 14.5 Logβ₁₃₃ 44.8 K₁₃₃ 14.4 Logβ₁₃₂ 42.7 pKa3(C) 2.1 Logβ₁₃₁ 39.6 pKa2(C) 3.0 Logβ₁₃₀ 35.6 pKa1(C) 4.1 Logβ₀₁₁ 9.8 pKa1(L) 9.8 Logβ₀₁₂ 12.3 pKa2(L) 2.5 Logβ₀₁₃ 12.3 pKa3(L) 0.0

The speciation plot in FIG. 16 shows that, with a pK_(a) of 2.5, the speciation analysis of Fe-Apo7435 system at about pH 7.4, 100% of the ferric chelate is uncharged.

Species % at pH 7.4 # of charges on chelate FeL₂H₂ 0.0 3 positive charge FeL₃H₃ 0.0 3 positive charge FeL₃H₂ 0.0 2 positive charge FeL₃H 0.00 1 positive charge FeL₃ 100.0 Neutral ferric chelate D. Apo7056

Proceeding in the same manner as described for Apo7323, the pKa values of Apo7056 and the Fe-Apo7056 system were determined, and the speciation of Fe-Apo7056 was constructed.

Logβ₁₁₁ 18.7 K₁₁₁ 18.7 Logβ₁₂₂ 35.9 K₁₂₂ 17.2 Logβ₁₃₃ 51.5 K₁₃₃ 15.6 Logβ₁₃₂ 47.3 pKa3(C) 4.2 Logβ₁₃₁ 42.3 pKa2(C) 5.0 Logβ₁₃₀ 36.5 pKa1(C) 5.8 Logβ₀₁₁ 9.8 pKa1(L) 9.8 Logβ₀₁₂ 14.7 pKa2(L) 4.9 Logβ₀₁₃ 15.1 pKa3(L) 0.4

The speciation plot in FIG. 17 shows that 97.5% of the ferric chelate is Fe(Apo7056)₃ in neutral form.

Species % at pH 7.4 # of charges on chelate FeL₂H₂ 0.0 3 positive charge FeL₃H₃ 0.0 3 positive charge FeL₃H₂ 0.0 2 positive charge FeL₃H 2.40 1 positive charge FeL₃ 97.5 Neutral ferric chelate

Based on these observed results, the amount of FeL₃ (neutral ferric chelate) at pH 7.4 depends on the amine pKa of the 3-hydroxypyridin-4(1H)-one, and also the amine pKas of the Fe-[3-hydroxypyridin-4(1H)-one] system. The ferric chelate system of Fe-Apo7435 shows 100% uncharged Ferric chelate FeL₃ at pH 7.4, while Fe-Apo7323 system shows 96.9% of uncharged ferric chelate. As the pKa of the amino function increases to about 6.1, as in the case of Fe-Apo7067 system, the ferric chelate remains a combination of charged species at pH 7.4 in about 87.6%. The above results show that the amino fluorinated derivative of 3-hydroxypyridin-4(1H)-ones of the present invention can be tuned to produce varying amounts of ferric chelate that is uncharged at pH 7.4, thus varying the amount of chelated iron that is able to pass through the blood-brain barrier.

Example 54

Pharmacokinetic Data of Apo7323, Apo7433, Apo7435 and Apo7448 Following Oral Administration to Rats

Adult male Sprague Dawley rats (275-325 g, Charles River Laboratories, Saint Constant, Quebec) were orally dosed with 50 mg/kg of test compound (Apo7323, Apo7433, Apo7435 or Apo7448) suspended in 0.5% carboxymethylcellulose (CMC) in water. For each test compound, samples were obtained from the plasma and brain of three animals per time point, at 0 (dosed with 0.5% CMC), 0.25, 0.5, 1, 2, 4, 8 and 12 h following administration. The concentration of the compound in rat plasma and brain samples was determined by HPLC-UV. Pharmacokinetic parameters were computed using the PKPlus Module in GastroPlus® ver. 8.0 (Simulations Plus Inc., Lancaster, Calif.). Calculation method: linear trapezoidal with linear interpolation.

Brain Plasma Plasma AUC_D_obs AUC_D_obs Brain Cmax_D Cmax_D CL Cpd (h · kg · μg/mL/mg) (h · kg · μg/mL/mg) (kg · μg/mL/mg) (kg · μg/mL/mg) (L/h/kg) Apo7323 1.010 1.630 0.218 0.400 1.99 Apo7433 0.039 0.860 0.400 0.396 3.76 Apo7435 0.122 0.516 0.102 0.312 6.61 Apo7448 0.486 1.07 0.178 0.334 3.12 

What is claimed is:
 1. A morpholinyl-containing fluorinated 3-hydroxy pyridine-4(1H)-one compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein: G¹ is CH₂NR¹R², where NR¹R² is morpholinyl; G² is CH₂CF₂R³; wherein R³ is F or H; G³ is H or C₁-C₄ alkyl; and G⁴ is H or C₁-C₄ alkyl.
 2. A morpholinyl-containing fluorinated 3-hydroxy pyridine-4(1H)-one compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein G¹ is C₁-C₄ alkyl; G² is H, C₁-C₄ alkyl or cyclopropyl; G³ is H or C₁-C₄ alkyl; and G⁴ is CH(R⁸)CF₃, wherein R⁸ is morpholinyl.
 3. A morpholinyl-containing fluorinated 3-hydroxy pyridine-4(1H)-one compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein G¹ is CH(R⁴)CF₃, wherein R⁴ is morpholinyl; G² is H, C₁-C₄ alkyl or cyclopropyl; G³ is H or C₁-C₄ alkyl; and G⁴ is H or C₁-C₄ alkyl.
 4. A morpholinyl-containing fluorinated 3-hydroxy pyridine-4(1H)-one compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein G¹ is CH(R⁷)CF₂H, wherein R⁷ is morpholinyl; G² is H, C₁-C₄ alkyl or cyclopropyl; G³ is H or C₁-C₄ alkyl; and G⁴ is H or C₁-C₄ alkyl.
 5. The compound of claim 2, wherein G¹ is methyl, G² is H, and G³ is H.
 6. The compound of claim 2, wherein G¹ is methyl, G² is methyl, and G³ is H.
 7. The compound of claim 1, wherein R³ is F, G³ is methyl and G⁴ is H.
 8. The compound of claim 1, wherein R³ is F, G³ is H and G⁴ is H.
 9. The compound of claim 3, wherein G² is methyl, G³ is methyl, and G⁴ is H.
 10. The compound of claim 3, wherein G² is methyl, G³ is H, and G⁴ is H.
 11. The compound of claim 4, wherein G² is methyl, G³ is H, and G⁴ is H. 